#geometry-and-trigonometry

1 messages Ā· Page 58 of 1

obtuse quiver
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i guess thats stating the obvious

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but the key is practice

heavy solstice
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help i dont know what to do im freaking out 😿

hard moon
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it doesn’t appear to have exactly one solution

north kindle
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I’m having trouble with this problem, Im trying something with a line from A to the perpendicular bisector of CB but it doesn’t seem to be working

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I think I have that EFA + BAC = 180

grave pond
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That would require EF to be horizontal..

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It should be EFA + 2BAC = 180­°.

north kindle
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Why exactly

grave pond
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It you draw a horizontal line through F, then its angle with FE and FC are both the same as angle BAC.

north kindle
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How do you know that

grave pond
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Because it's parallel to BEDA.

north kindle
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How do you know that

grave pond
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Because that's what I deined my line to be.
Angle FEA = angle BAC because isosceles triangle.
Angle KFE = angle FEA because parallel lines
Angle KFC = angle BAC becaluse parallel lines.

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So angle EFC is two times angle BAC.

north kindle
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Damn

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I must’ve gotten something wrong in my algebra somewhere

grave pond
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And then angle ECF = angle EFC, again because isosceles triangle ...

upper karma
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I thought tangent lines were all the same lenght at intersections

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but it has coome to my attention i am critically wrong

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I am off about 2 when I multiply 23.2 (One whole triangle side lenght) by 3

grave pond
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You're probably assuming that the three points of tangency are 120° apart on the circle, but that cannot be true.

upper karma
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how do i approach this then

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I have 3 points, they are all tangent (Questions states: "If line appears tangent, then they are tangent"

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Im going to label the image for easier explanation'

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i forgor the C šŸ’€

grave pond
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I don't know what it is you're computing, but you can find all the side lengths using this:

hard moon
maiden brook
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i love aops

north kindle
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It is

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I got it btw

maiden brook
north kindle
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Why is it necessarily true that they share an altitude?

dark sparrow
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from B onto AC

north kindle
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Yes

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Why is that necessarily both of those triangles altitudes

dark sparrow
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i mean we are considering AX and CX as their bases arent we

north kindle
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Yes

dark sparrow
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so like

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those two come from the same straight line

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so of course the altitude dropped from B will be geometrically the same in both cases

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not merely equal length but like the segment is one and the same for both

north kindle
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Ok but like, why is that segment the altitude

dark sparrow
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what's your defn of an altitude of a triangle

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it ought to be something equivalent to "a segment from one of the vertices to a point on the straight line containing its opposite side, and perpendicular to said line"

north kindle
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Yeah

dark sparrow
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yeah os

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so*

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i think you're overthinking it

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we are literally just dropping a perpendicular from the same point (B) onto the same straight line (AC) in both cases

north kindle
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How is BX perpendicular to AC

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Or I guess BD

dark sparrow
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nobody said BX or BD are perp to AC

north kindle
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Looks about right

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What about the other one though, how have we shown they are the same

dark sparrow
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wym??

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this red segment is the literal altitude for both triangles

north kindle
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How?

dark sparrow
north kindle
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Oh wait I see I think

dark sparrow
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if you drop a perp from B onto the line containing XC, to construct the altitude of triangle BXC, you get BH

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if you drop a perp from B onto the line containing AX, to construct the altitude of triangle BAX, you still get BH

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it's literally the same one

north kindle
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Ok that makes sense

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Thanks

upper karma
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I need Help with option C,D

dark sparrow
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holy shit they missed some important punctuation in there

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  • ABCD is a tetrahedron.
  • Face BCD is equilateral, with side length 12 units.
  • H is the foot of the perpendicular from A onto BCD, and it lies inside the face.
  • The area of CDH is 3 times that of BCH.
  • The area of DBH is 2 times that of BCH.
  • M is the midpoint of side BD.
upper karma
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I understood the question

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It is clear?

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What to do ?

dark sparrow
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well i needed to write it out like this to make any sense of it.

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cause the run-on sentence going on there is insane

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anyway... do you have a diagram of this thing?

upper karma
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Nope

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They didn't give any

dark sparrow
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i'm not asking if they give one

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i am asking whether you have even thought to make one

upper karma
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Oh yes yes

dark sparrow
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"do you have [thing]" is not, in general, the same question as "does the problem give you [thing]".

upper karma
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My bad , I am sorry

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By any chance, is the foot of A on plane BCD THR CENTroid ?

grave pond
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I think Ann wants to see your diagram.

dark sparrow
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^

upper karma
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Oh

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I do realize the fact that BCD does not look like an equilateral triangle

dark sparrow
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ok let me remind you once again

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hidden edges are drawn with dotted lines

upper karma
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I do remember that,but drawing it this way make me to visualize it in a easy way

dark sparrow
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it's actually way easier if you do it my way

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that way you actually get a sense of the picture being 3D lol

upper karma
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Okay I will do it from now on

dark sparrow
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also i don't see H anywhere

upper karma
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H won't be usefully for options C AND D

dark sparrow
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i would not be so sure

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the position of H relative to B, C and D seems relevant!

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especially given A is directly above it

upper karma
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OHHH

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I forgot that point

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1 min

dark sparrow
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i also recommend you make a subdiagram showing only face BCD

upper karma
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Okay

dark sparrow
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cause the area ratios between CDH, BCH and BDH should be more easily shown on that

upper karma
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(I know how my x looks like)

dark sparrow
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Ʀ is an interesting choice of letter for area

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anyway i am pretty sure the distances of H to each side can just be computed directly.

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knowing BC=CD=DB=12 and these area ratios

upper karma
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Yes

dark sparrow
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do that

upper karma
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Yrs

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I already got it...

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Option C and D

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That is what i need help with

dark sparrow
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drop the perpendiculars from H onto each side of the triangle

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give names to each of the three points that are their bases

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and send a photo of the resulting diagram here

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mark their lengths as well

upper karma
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šŸ‘

dark sparrow
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ok

upper karma
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CHF are not collinear

dark sparrow
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ok so you want the distance from A to CM...

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and the logical first step to that is to find the distance from H to CM

upper karma
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Okay i will try to

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Yay

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Got it

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The perpendicular distance is 2

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2

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So now we can use pythogorean theorem

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Thanks

obtuse quiver
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solve $cos(3x-15^{\circ}) = \frac{\sqrt{3}}{2} for, 0 \leq x < 180$

dark sparrow
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did you mean \leq?

obtuse quiver
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oh yeah

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shit

somber coyoteBOT
obtuse quiver
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I got the reference angle and everything

dark sparrow
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solve $\cos(3x-15^{\circ})=\frac{\sqrt{3}}{2}$ for $0\leq x\leq 180^{\circ}$

somber coyoteBOT
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|Ann⟩

obtuse quiver
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but normally the quadrants are like 90 180 270 and 360 right in a range of 0 to 360

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i can't wrap my head around the changed ranges

west radish
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15

obsidian harness
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cause wolfram can do it for them ofc

dark sparrow
west radish
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As do cosinverse on the other side it will equal 30 then add 15 which will equal 45 and then divide by 3

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Which equals 15

obtuse quiver
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but i'm trying to know what to do when the range is changed

west radish
obsidian harness
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And x = 15 is only one solution ofc

dark sparrow
obtuse quiver
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i got x=15, 115, and 135

obsidian harness
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,calc 3*135-15

somber coyoteBOT
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Result:

390
obsidian harness
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you're not at the upper limit yet

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Let me doublecheck

west radish
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180 minus answer

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Or 90 plus answer

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As quadranta

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Quadrants matter

obsidian harness
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Ah yes you are

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Yeah see what happens when you try to find the next highest solution

obsidian harness
obtuse quiver
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all i wanna know is what to do when the range is changed, at school they drew something on the quadrants

dark sparrow
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imo the best way to do this is to solve for x in R and then filter to your range

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instead of trying to memorize a thousand procedures for what to do when the range is in this or that form

west radish
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If the range is changed like to 360 then minus the ansr with 360 or with 270 or with 180

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According to what the range is

dark sparrow
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cos(t) = sqrt(3)/2 <=> t = ±pi/3 + 2pi*n, where n ranges over all integers

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or in degrees ±60 + 360n

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3x - 15 = ±60 + 360n and solve for x as normal

obtuse quiver
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ohh

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now i got it

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thanks

obsidian harness
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np

dark sparrow
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augh

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sorry. 30, not 60

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typo on my part.

obtuse quiver
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all good, thanks ann

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btw is this correct $cos\theta = \frac{2}{3} , -180\leq x <180 \newline reference angle=48.1^{\circ} \newline \theta=-131.9,131.9$

somber coyoteBOT
dark sparrow
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,calc cos(48.1 deg)

somber coyoteBOT
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Result:

0.66783255547105
dark sparrow
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as long as you recognize that 48.1° is an approximation, yes.

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wordbadtex though.

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er wait

obtuse quiver
dark sparrow
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no

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why ±131.9 and not ±48.1?

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cos(131.9°) is **-**2/3 ish.

obtuse quiver
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one sec let me show you this

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i drew this quadrant to do that problem

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instead of 0 and 360 i put in -180 and 180

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because the range was changed

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and then -180+48.1 and 180-48.1

dark sparrow
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... hold on

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these should both be on the left.

obtuse quiver
obtuse quiver
dark sparrow
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angles are always measured from the positive x axis. the positive x axis is always 0, or an integer multiple of 360.

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-180 to 180 still sweeps out a full circle exactly once but it doesn't start on the positive x axis

obtuse quiver
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ah

dark sparrow
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it starts a half turn across from that

obtuse quiver
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so i should've done this

dark sparrow
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upside down

obtuse quiver
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is this good

dark sparrow
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worse

obtuse quiver
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shit

dark sparrow
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the ±180 are in the right places but the 0 and 90 are both misplaced and unnecessary.

obtuse quiver
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alright so ignoring the 0 and 90

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how would i proceed

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i have the reference as 48.1

dark sparrow
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... you would get x = ±48.1 but the whole construction of your diagram makes it nigh impossible to justify that cleanly.

obtuse quiver
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could you tell me how to do it from scratch

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if it doesn't take up too much of ur time

dark sparrow
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afraid it will

obtuse quiver
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ah no problem then

rapid rivet
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I was following a video online on how to graph cos and sin equations. I was a bit confused why they replaced the 2 in the formula solving for period 2pie/b as 3pie/(1/3) i was thinking because the amplitude is three that’s why but i’m still a bit confused if there is like a rule for it

dark sparrow
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can you link the video

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also $\frac{3\pi}{1/3}$ is not even equal to $4\pi$ lmao

somber coyoteBOT
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|Ann⟩

rapid rivet
dark sparrow
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huh

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wow ok he's just plain wrong there

rapid rivet
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oh dang

dark sparrow
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a comment from the video to that effect

rapid rivet
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OH

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okay ty i was so confused

dark sparrow
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yeah

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the period should be 2pi/(1/3) = 6pi

rapid rivet
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watching on my school account so the comments were turned off

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okay thats what i thought thank you!

steady mason
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is the range and domain of a cubic function always infinity unless said otherwise

dark sparrow
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it's not "infinity"

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it's all real numbers.

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or (-āˆž, +āˆž),

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or just R.

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but yes.

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and the same goes for any polynomial function of odd degree.

static hearth
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if sin(alpha) is equal to -4/5 in quad 4, does this mean that sin(theta) also has the same ratio of -4/5? what is the difference between them, exactly?

steady mason
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.close

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oh

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right

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dumb me

dark sparrow
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thats the difference

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you cannot tell anything about sin(Īø) from only the info you wrote here

obtuse quiver
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,rccw

somber coyoteBOT
obtuse quiver
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Any help on the trig question

amber hollow
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any advice? i did P = 2 so B = pi, and midpoint = 7+1/2 = 4, and amplitude = 7-1/2 = 2, and since it starts at 0 im assuming its a flipped cos function

dark sparrow
lime crownBOT
# static hearth

Please do not trust ChatGPT or similar AI tools for mathematical tasks, as they often generate output which "sounds correct" but has numerous factual or logical errors. Use of these AI tools to answer other people's help questions is strictly against server rules (see #rules).

dark sparrow
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@static hearth sin, cos and tan still denote the same trig functions no matter which letter you write for their input. but if a problem involves two different angles, one of them called α and the other θ, then you obviously have to distinguish between values of trig functions at alpha and those at theta

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like idk how to explain it except to repeat the same shit 17000 times

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only to have you fire off this fucking GPT shit

static hearth
static hearth
dark sparrow
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the problem will tell you all the letters it uses.

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they are greek but they are just letters

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so yeah

static hearth
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for instance, here I believed that on A) I had to calculate the Beta value in the context of sina = -4/5

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but you just go over on the right side and find beta in the context of tanB = 4/1 right?

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ew wtf. <@&268886789983436800>

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good. it’s gone

dark sparrow
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to find shit for alpha you work with alpha

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to find shit for beta you work with beta

static hearth
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so for this, which is just a reference I put on my wall, why would sin(a) = sin(a)cos(B) ?

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why wouldn’t sin(a) just equal sin(a)

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bahhh nevermind.

elder anchor
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I do not see sin(a) = sin(a)cos(B) in your notes

obtuse quiver
west tundra
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can i get an answer and explanation for this problem, I know to take inverse and use inverse of tan but I get -0.174 and 2.967 but mathaway says its wrong

zealous olive
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and this problem has infinite solutions

clear owl
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Why can’t I understand this? I’m stupid that’s what

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Idiot here trying to actually be good at trig, what a fool I am

ruby flame
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x = 10cos(60) i think

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which is 5

clear owl
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Well, I check and yeah, it’s 5

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My apologies, it’s just that my math anxiety tends to get the best of me

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Grade 11 math hasn’t been that kind to me

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Anyway to find another method to get the same result as in ink? (52.23)

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Yeah

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I tend to worry a lot because I sometimes feel like my teacher does not get that I AM trying to understand, but everything feels so cramped and doesn’t have enough space to breath, I do well in all my other classes, but math annoys me the most

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Like the problem above as I do not know HOW anybody could find a second method to the question without the use of a second side for the pythagorean theorem

trail tendon
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you can use sin of one angle or cos of the other angle

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and you can find the other angle because all the angles add up to 180

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oh wait

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it probably wants you to do pythagorean theorem

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oh

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i forgot you just said without pythagorean theorem

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lol

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theres actually a lot of ways you could do it

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also it doesn't say not to use pythagorean theorem...?

clear owl
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The paper was made weirdly

trail tendon
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yeah

clear owl
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Gotta love grade 11 math for uni (Hell is real)

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/j

trail tendon
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i bet it wanted you to use pythagorean theorem

clear owl
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Yup and that was supposed to be the Correct Answer BUT, the side didn’t have any other values

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But it’s okay

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I am focusing on other stuff

clear owl
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All the stuff from the previous quizzes

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I dk why this was graded weirdly

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I’m sure I showed all my steps

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Isn’t cot literally cos/sin? Therefore making if x/r / y/r

trail tendon
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i think it may have wanted to you multiply by the reciprocal

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idk

clear owl
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And this is weirder

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I tried to solve it as best as I could using the Pythagorean identity

trail tendon
#

ngl i have no idea what you did

ruby flame
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use difference of squares

trail tendon
#

maybe not šŸ’€

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i guess they might have just wanted him to multiply it out like (1-sinx)(1+sinx) = 1 - sin^2(x)

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but thats not really a proof

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i thought it wants him to prove cos^2(x) = 1-sin^2(x) after distributing

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but maybe not

clear owl
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Yeah

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I tried to do it using this

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That wasn’t my best idea

trail tendon
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yeah, if you can assume that then thats the way

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but i don't think you distributed correctly

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that might be the problem

clear owl
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But I now know

trail tendon
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i'm not entirely sure what you did

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lol

clear owl
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How to do it

trail tendon
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yeh

clear owl
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I just had to times them together

trail tendon
#

yeah

clear owl
#

And then use that identity

trail tendon
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yeah

clear owl
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And cross the sinses? Out

ruby flame
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but why is difference of squares not a good proof

clear owl
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For the cos^2x

ruby flame
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you would use the pythagorean identity

trail tendon
jagged wyvern
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Could someone help me with this? At first I tried using surface area of a sphere using 4pi(r)^2, but it marked it wrong, then i found out if it was half a sphere it would be 2pi(r)^2

Both are wrong?

ruby flame
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you need to account for the circle base

trail tendon
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sphere*

jagged wyvern
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Im not sure

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Thats what I found on google

trail tendon
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i dont know exactly what a hemisphere is

ruby flame
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hemisphere is half a sphere

trail tendon
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assuming it is exactly half a sphere

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ok

ruby flame
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from google

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the problem is you didn't account for the base

clear owl
#

?

jagged wyvern
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radius

jagged wyvern
ruby flame
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add an extra pi r^2

trail tendon
#

huh?

jagged wyvern
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So what should the formula look like

ruby flame
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$$3\pi r^2$$

jagged wyvern
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If sphere is 4pi(r)^2

somber coyoteBOT
#

jasoney

trail tendon
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what??

ruby flame
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because when you cut it in half there is a circle at the bottom

trail tendon
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isn't the volume of a sphere like (4pir^2)/3?

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oh

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mb

ruby flame
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surface area

trail tendon
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surface area

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ahhh i see

jagged wyvern
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Hm alr

clear owl
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Then it should be 226.19 2pi (6) ^ 2, 2pi x 36 or 6.283 x 36 = 226.188 or 266.189

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Make use of bed as

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Bedmas

jagged wyvern
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339.29

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Uh could someone confirm? It doesnt let me check no more

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If im rounding to nearest hundreths

trail tendon
#

uh

ruby flame
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i got 339.29

trail tendon
#

how?

ruby flame
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3pi(6^2) = (3)(36)pi = 108pi = 339.29

trail tendon
#

4pir^2 is the surface area of entire circle tho

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so 2pir^2 should be half circle...

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i missing sum?

ruby flame
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but when you cut it in half you add a circle on the bottom

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to close it

jagged wyvern
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I tried using 2pir^2 it was wrong

trail tendon
#

oh

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oh gotcha

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i see

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loll

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yea u right

jagged wyvern
#

Can someone explain how i got this wrong? I solved for the radius using the given circumference. I kept the radius in fraction form for better approximation

29.5/(2pi)

V = 4/3pi(29.5/2pi)^3
= 433.53 if rounded to nearest hundreth

trail tendon
#

that is....very weird

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uhh

hard moon
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That’s not even wrong

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yeah idk

trail tendon
#

yeah

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idk

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XD

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ur program is just dumb maybe šŸ’€

hard moon
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it may be displaying the correct answer after all tries have been attempted

dark sparrow
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,calc 4/3 * pi * (29.5/(2 * pi))^3

somber coyoteBOT
#

Result:

433.52590365166
jagged wyvern
#

Bruh

hard moon
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oh we got it wrong, then

jagged wyvern
#

šŸ¤·ā€ā™‚ļø

dark sparrow
#

??

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ok wait

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,calc 4/3 * 3.14 * (29.5/(2 * 3.14))^3

somber coyoteBOT
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Result:

433.96579644881
dark sparrow
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no, can't be that

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it smells like some kind of rounding fuckup tho

faint pasture
dark sparrow
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,calc 4/3 * 22/7 * (29.5/(44/7))^3

somber coyoteBOT
#

Result:

433.17712637741
faint pasture
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Oh lmao

slate frost
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can someone please help me with this?

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its permutation

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but idk how to find the favorable outcomes

faint pasture
dark sparrow
faint pasture
slate frost
faint pasture
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Choose two out of the 4

slate frost
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i used permutation to find total outcomes (360)

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prbability = fav outcomes/total outcomes

faint pasture
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,calc 654*3

somber coyoteBOT
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Result:

360
faint pasture
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How many ways can you select 2 from 4?

slate frost
#

my teacher said the fav outcomes was 12 in his notes but idk how he got 12 for fav outcomes

slate frost
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oh its 12

faint pasture
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Yep

slate frost
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so i have to use the formula twice

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once for total outcomes and once for fav

faint pasture
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Yep

slate frost
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thanks

gaunt iron
#

<@&286206848099549185>

hard moon
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Try showing it’s a parallelogram; you’re almost there, then use the fact that opposite angles of a parallelogram are congruent

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Alternatively, prove two triangles containing those angles are congruent

foggy gust
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In a parallelogram, the acute angle is 45 . Find the area of a parallelogram
if its diagonals are 6 cm and 8 cm.

can someone help me with this task please

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i dont quite understand it

obsidian harness
foggy gust
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yes

obsidian harness
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And the centre bisects both diagonals

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So we have 2 * (1/2 * 3 * 4 sin 45) + 2 * (1/2 * 3 * 4 sin(180 - 45))

foggy gust
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but that gives us approximately 11.27

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but the correct answer is 7 as i was told but how do we get 7

foggy gust
#

yes

obsidian harness
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You could try using coordinate geometry

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Then we must have (a + h)^2 + h^2 = 8^2, (a - h)^2 + h^2 = 6^2 if a is the base and h is the height

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So (a + h)^2 - (a - h)^2 = 4ah = 28

upper karma
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Status 1

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Correct channel,right?

obsidian harness
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Btw, use Approach0 to search for answers to competition problems

upper karma
#

I will be back after the problem is precalc is done

obsidian harness
#

ok

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The first link in Approach0 tells you that tan y = sqrt(2)/2

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So options A and C are incorrect

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in fact it's B

upper karma
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Yes,the correct answer is B

upper karma
#

The original one's are of a different level

obsidian harness
upper karma
#

That is why I ask them here

obsidian harness
#

RIP

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but no worries ig

upper karma
#

Got this one though

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Thank you

obsidian harness
#

np

rotund stump
#

can someone explain how this works and how this is able to rotate a absolute value function

faint pasture
#

Are you sure that is all the context?

upper karma
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If area of ​​the triangular region AQP is 50
What is the area of ​​square ABCD

#

5(PB)=12(PQ)

proud nest
#

Its saying this is correct, but in the wrong form

#

oh it was 1/sqrt11

round gale
#

a and b was easy but for c I tried setting 2sin2x=root2 which gave pi/8 for quadrant 1 (which was correct) I did the same for quad 2 I got 7pi/8 and that wasn't correct The answer key said the answer is x=-pi/8,x=9pi/8, x=3pi/8, and 11pi/8. Can someone explain?

faint pasture
#

Do you know the formula for 2cos(a)cos(b)?

upper karma
#

help

#

i forgot to study so uh help

#

i remember first do some triangle?

#

Then get midpoint of each line?

hard moon
# upper karma

if you construct a perpendicular bisector of segment AB, then every point on that perpendicular bisector will be same distance from A as is to B

Likewise, if you construct a perpendicular bisector of BC, then every point on that perpendicular bisector will be the same distance from B as is to C

#

How can you use that to find a point (the boat) which is the same distance away from all three points A, B, and C?

clear owl
#

Any clues on how to find the measurement of D to G?

#

Would I have to find the ā€œheightā€ of the second triangle?

wicked island
#

how can I prove that a>b?

trail tendon
#

maybe you could do it using law of cosines?

wicked island
#

good idea, but I'm not sure I can use it already, considering the book didn't prove it yet

hard moon
#

hinge theorem

trail tendon
#

šŸ˜”

wicked island
maiden brook
#

cos 100 < cos 80

#

that’s all u need

#

cause cos 100 is negative

grave pond
#

If you don't have any trigonometry: Drop a perpendicular from A towards BC, meeting it in P, such that the triangles ABP and ACP are right. Then use the fact that BP > PC and Pythagoras.

daring compass
#

do i ask geometry questions here instead of in the help section?

grave pond
#

Each is accepted, just please don't do both.

sudden shell
#

I don't know how to do both of the problems

buoyant kraken
#

I believe that for the first one it is angles KIR and KER because they are both opposite of the diameter.

#

for the second one I believe it is FHG and FYG for the same reasons

rotund stump
#

is it possible to rotate this or no

haughty tangle
#

Somebody help please

primal jasper
haughty tangle
#

Like on how to start. I'm so stuck

primal jasper
#

Alright so lets do the simple parts first, so when you have a line interesting a line?

haughty tangle
#

They meet at a single point right?

primal jasper
#

Yes but it’s also split into four parts right?

haughty tangle
#

Oh yeah

primal jasper
static hearth
#

I just failed my trig class. anyone have an online resource/mega test that I can study so that next semester I pass for sure?

haughty tangle
primal jasper
haughty tangle
#

If not sure if I’m correct but the half circle isn’t it 180 degrees

primal jasper
#

Exactly

haughty tangle
#

:0

primal jasper
# haughty tangle :0

If you have one part of that 180, you can subtract that part from 180 to find the other part.

primal jasper
#

Ones right next to the angle are ones that will ā€œcompleteā€ the angle making it 180. And the ones opposite of it are just the same as the angle

haughty tangle
#

oh yeah the supplementary angles

#

i think

primal jasper
#

Yup!

haughty tangle
#

phew

#

quick question on the 25 degress its called a vertical angle right

#

so is 40

#

and 155?

primal jasper
#

Vertical angles is the rule that says opposite angles are always congruent (the-same)

haughty tangle
#

oh yeah their congruent

primal jasper
#

Do you know what the || means in a||b

#

Okay discord doesn’t like me

haughty tangle
#

in ab?

primal jasper
#

But the do you know what this means |

#

When in between the a and b

haughty tangle
#

oh

#

In geometry its a notation where for example a is parallel to line b just like c||d

#

so its just saying the parallele line are in the same plane that never intersect

trail tendon
#

| |

primal jasper
#

Mhm!

trail tendon
#

oh

#

i see

haughty tangle
#

yeah

#

that why they put it in these line ||

#

so i tried one on my own and idk if its correct so lemme send it

#

cause 130+50=180

primal jasper
#

Yup perfect!

haughty tangle
#

Yay 😭

#

I’ve only done these two so far

#

This one Cuase it’s the same thing like the first one

#

So I have measures 1 and 3

#

and 2 because I noticed 1 and 2 are the same degree 130

primal jasper
haughty tangle
#

becuase their on the same line

#

i think it has a name

#

im not sure tho

primal jasper
#

Yes, but not quite. It’s because the two lines intersecting that line are parallel

haughty tangle
#

ooh

primal jasper
#

If they weren’t parallel or if not stated they are, you can’t assume that.

haughty tangle
#

wait

#

is it corresponding?

primal jasper
haughty tangle
#

oh so thats what i saw

primal jasper
#

The 130 to the 130 & 50 to the 50 are corresponding angles

haughty tangle
#

thats pretty simples

primal jasper
#

So what would be the relationship between 1 & 5

haughty tangle
#

Corresponding?

primal jasper
#

Exactly

haughty tangle
#

o

primal jasper
#

What about 1 to 8

haughty tangle
#

hnm

#

idk if this is the name

#

but

#

same side extrior

zealous olive
#

supplementary

haughty tangle
#

yeah ss exterior is supplementary aswell

primal jasper
#

Exactly, which means they are supplementy

haughty tangle
#

lets go

primal jasper
#

What about 4 to 5

haughty tangle
#

same side interior

#

which i also think is supplementary

primal jasper
#

Mhm!

#

And then 4 to 6

haughty tangle
#

alt interior

#

or alternate

primal jasper
#

Which means the angles are?

haughty tangle
#

congruent

primal jasper
#

Nice

haughty tangle
#

thank god i thought it was supplementary for a second

primal jasper
#

You should be able to complete your assignment pretty easily with that

haughty tangle
#

Ok lemme try

#

can i send it on here to make sure im correct?

#

when im done

primal jasper
#

Mhm

haughty tangle
#

šŸ‘

haughty tangle
#

Now I just hope I didn’t mess up

#

sorry for bad lighting and quality and messy hand writing 😭

primal jasper
haughty tangle
#

Yessss Thank you for you help!!! I just needed a refresher ā¤ļø

primal jasper
#

Ofc ofc!

autumn pelican
#

I really feel stupid right now

I can't figure out how to do (sin(x)+cos(x)) ^2

In my brain I think it'll be sin^2(x) + 2sin(x)cos(x) + cos^2(x) but then a math app tells me the answer is sin(2x) + 1

zealous olive
#

sin^2(x) + cos^2(x) = 1
and
2sinxcosx = sin2x

autumn pelican
#

I think I am lost, why are those the same

zealous olive
#

trig identities

#

you probably haven’t learned them yet

autumn pelican
#

I'm in the process of learning them but this is my first day so far

#

Oohh.. so for Pythagorean identities I can add the sin^2 + cos^2 to equal 1, but 2sin(x)cos(x) still confuses me

#

Nevermind I found it, I forgot about double angle identities

surreal escarp
#

How would I get x without cancelling it both

dark sparrow
#

(x+8)^2 is not equal to x^2 + 64.

#

@surreal escarp

surreal escarp
dark sparrow
#

dumb example: if x were equal to 2, then
(x+8)^2 would be (2+8)^2 = 10^2 = 100
but x^2 + 64 would be 2^2 + 64 = 4 + 64 = 68

#

either recall how to expand (a+b)^2, or expand (x+8)(x+8) the long way.

surreal escarp
#

i see

#

so 256+x^2 = x^2+16x+64 instead?

dark sparrow
#

yes of course

#

in general (a+b)^n is not equal to a^n+b^n. powers don't distribute over addition like that.

surreal escarp
#

so what should i do now

dark sparrow
#

how would you solve the equation

x^2 + 256 = x^2 + 16x + 64

if it was given to you like that to begin with?

#

what first step would you take

shrewd haven
#

Get the X’s by themselves?

surreal escarp
#

square root the x

dark sparrow
surreal escarp
#

or minus the 256 on both sides

shrewd haven
dark sparrow
#

why not just subtract x^2 from both sides?

surreal escarp
#

oo

#

i got x=12

surreal escarp
dark sparrow
#

yup there you have it

gaunt iron
#

@dark sparrow do yk how to do my problem ive been stuck on it for a while plz

dark sparrow
#

i am not going to even touch it

upper karma
#

Does anyone know how to do this?

#

😭

dark sparrow
#

there are people on this server who know how to do this, yes.

#

@upper karma what is troubling you here?

upper karma
#

I don't know where to start

dark sparrow
#

ok so you have a circular sheet of metal and you are cutting a hexagon out of it.

#

everything inside the circle but outside the hexagon is the scraps that they ask you about.

#

do you understand this? y/n
(i am not done yet, but i am bringing you up to the same page as myself)

#

@upper karma

dark sparrow
#

ok

#

so the scrap area equals the area of the circle minus the area of the hexagon.

#

do you see how to continue?

autumn pelican
#

If I am prompted cot = 2/3 and sinx > 0 and then asked

sin2x

Would my answer using the double angle identity be

sin2x = ~1.2569

or

sin2x = 12/13

I can't remember if I replace sin(x)cos(x) with that or if I compute it. Forgive me I have been working for 15 hrs straight and I am tired

dark sparrow
#

how did you get 1.2569

#

also go take a fucking nap for gods sake

#

15 hours straight is like a million times longer than you should be working

autumn pelican
autumn pelican
dark sparrow
#

what. why are you evaluating the sine of 3/sqrt(13) radians.

#

???

trail tendon
dark sparrow
#

you got yourself royally confused.

autumn pelican
#

I have lost the barrier between knowing what tf radians and degree mode does atm

dark sparrow
trail tendon
#

oh yeah its less than one second

autumn pelican
#

Was I right to still compute the sin and cos but meant to do this in degree mode?

trail tendon
#

half a second

#

šŸ’€

dark sparrow
autumn pelican
#

Oh, so I wasn't meant to compute the sin and cos

#

so 12/13 was correct?

dark sparrow
#

...

#

i mean you weren't meant to try to get x itself.

autumn pelican
#

I.. am even more cdonfused now, let me just take a picture of the question

#

From my fading mental capacity only thing I could deduce is to use double angle identity

dark sparrow
#

give me a couple minutes to clock in to work

autumn pelican
#

Sure, I'll just write what I did rq

#

What I did was

find hypot = sqrt13

sin2x = 2sin(3/sqrt13)cos(2/sqrt13) = ~1.2569
or
sin2x = 2(3/sqrt13)(2/sqrt13) = 12/13
#

I finally discovered I was dumb and not meant to compute it, the 2nd option was right (Dear God I hope)

dark sparrow
autumn pelican
#

It only gets worse from here bleak

dark sparrow
#

95% of it getting worse is because you have overworked yourself

autumn pelican
#

Oh 100% but if I don't I get a lovely zero

#

All I have left is another of these but with half angle and then a power reduction and something I don't even know

#

Could someone quickly confirm for me if the U in half angle identities for.. say sin(u/2) is equal to y/c?

spiral lodge
#

What are y and c?

autumn pelican
#

opposite = y and hypotenuse = c

spiral lodge
#

And what is u?

#

Without any picture it's impossible to answer

autumn pelican
#

u as in the half identity u (I think)

spiral lodge
autumn pelican
#

Oh okay great, ty

spiral lodge
#

U is just a name for the angle, you can use whatever letter you like

autumn pelican
#

ah okay

#

Ok I am swinging back full circle, if I don't have radians to easily get cosu do I replace cosu with -4/5 if my opposite is -4 and hypot is 5?
to make it

+- sqrt( 1-(-4/5) / 2 )
#

Coincidentally my teachers lecture has the exact same problem on the quiz, so nvm I can figure this out

upper karma
#

Status 1

dark sparrow
#

cos ec typesetting fail lmao

upper karma
#

?

dark sparrow
#

they tried to type cosec as in cosecant, but whatever software they used for typesetting took the first three letters as meaning cos

upper karma
#

Oh

dark sparrow
#

it is an inconsequential but noticeable typesetting defect

#

csc anyway...

#

(i don't know how to do this problem without headache)

upper karma
#

This is what the solution says(Screen shot was not allowed so I had to write it down)

dark sparrow
#

you mean 2^(r-1) and not 2^(n-1) in the sum?

upper karma
#

Something to remember or can it be derived in a easy way ?

dark sparrow
#

no idea how they would derive it

#

it looks annoying

upper karma
#

Okay

nocturne remnant
upper karma
#

Induct?

#

Induction .

#

?

#

Anyway

#

Guessed it

#

Status 1

autumn pelican
#

Is this all the question is asking me to do?

#

Sorry let me flip that

upper karma
#

,rotate

somber coyoteBOT
autumn pelican
#

That works, ty

dark sparrow
#

expand this

#

you will get a cos^2(2x)

#

apply that identity again

autumn pelican
#

Got it, thanks I'll do that rq

#

Why isn't it cos^2(4x)?

#

Oh wait, nvm

upper karma
autumn pelican
dark sparrow
#

but also definitely not.

autumn pelican
#

sorry lmao I thought it was going to look better

#

Yeah I figured 😦

dark sparrow
#

show your work so i can tell you where you screwed up.

autumn pelican
#

,rotate

somber coyoteBOT
dark sparrow
#

cos^2(2x) = (1+cos(2*2x))/2.

#

(1+cos(2x))/2 would be cos^2(1x) and not cos^2(2x).

autumn pelican
#

oh okay so the 2 * goes inside the cos not on the outside of the parenthesis

dark sparrow
#

..... yes obviously since you are working with cos^2(2x) and not with 2cos^2(x)...

autumn pelican
#

So right after I convert cos^2(2x) it should look like

( 1 + 2cos(2x) + ((1 + cos(4x)/2) ) / 4
```?
upper karma
dark sparrow
upper karma
#

For the first time

dark sparrow
#

it's more like i don't want to touch that problem.

upper karma
#

Oh

autumn pelican
#

It's all for naught, I can't finish all these questions in time 😦

obsidian harness
#

You can write cos^4 x in terms of a constant, cos 2x, and cos 4x

faint pasture
upper karma
obsidian harness
upper karma
#

Both

autumn pelican
#

I CAN SLEEEPPP I submitted it a whopping 4 minutes before I would have gotten 0 points. Fuck college

upper karma
#

South?

obsidian harness
upper karma
#

Cba?

fiery summit
obsidian harness
obsidian harness
upper karma
#

Okay

#

In which category does complex numbers come under ?

dark sparrow
upper karma
#

Okay thank you

gilded egret
#

hey guys

#

any1 good at like cosine proofs?

lime dune
#

!da2a

lime crownBOT
#

No need to ask ā€œCan I ask…?ā€ or ā€œDoes anyone know about…?ā€ā€”it’s faster for everyone if you just ask your question! See https://dontasktoask.com/

zealous olive
gilded egret
#

so uh

#

triangle with A 38degrees, B 55degrees, C 87degrees and a 14m, c and b are unknown and they want me to find out what c is

lime dune
#

that’s not ā€œcosine proofā€???

#

law of sines instakills it

gilded egret
#

oh i already got proofs down i meant like

#

well i would love some help understanding it

#

but

#

this

#

sorry for crude drawings

gilded egret
lime dune
#

there is nothing particularly deep going on here

#

just plug into law of sines and solve for c

#

a/sin(A)=b/sin(B)=c/sin(C)

upper karma
#

Nvm sorry oops

bronze wind
#

can someone give me the step by step process of solving for the surface area of this figure? Im stumped and I have gotten like 5 different answers

(I just need the process, I know that this answer here is correct because I checked the answer key to the assignment)

silent plank
#

can you show your most recent attempt

bronze wind
#

I erased it

#

I just need to know how to use the formula

#

because I currently have no idea how to plug the numbers in

silent plank
#

area of each face (there are 5)

#

doable with basic area of rectangles and triangles

#

then add them all up

#

the 30in side length you calculated is correct btw

bronze wind
#

do you have like the actual formula im supposed to use for a polyhedron

#

and do you know how I would plug it in for this particular scenario

silent plank
#

general formula would be
add up area of each face/surface

bronze wind
#

ok

silent plank
#

there are formulae for certain solids,
but that's where they come from, so better off remembering that instead
instead of a different formula for each one

bronze wind
#

yeah its weird because our instructor had us remember a specific formula for a polyhedron and it makes little sense

obsidian harness
#

ew

#

memorisation

silent plank
#

priority is to remember where stuff comes from

#

if you rely fully on memorising formula and don't know where they come from
and you for some reason forget or misremember, you're screwed

bronze wind
#

unfortunately public education thinks that everything is needed to be memorized

sharp ruin
#

Heyy
Can somebody help me derive the formula for the excenter of a triangle?
I know it would require me to use external angle bisector theorem but I can't figure out how can I do that?

ebon swallow
#

can someone help me with geometry and solving for volume

pale spire
#

Given the positions of the Moon, Alice, and Bob, find the length of the shortest path that starts at one of the players, touches (or crosses) the edge or the interior of the Moon, and ends at the position of the other player.

sudden shell
#

Can someone explain this to me someone told me the answer was 80 but I need to understand how it’s 80

trail tendon
sudden shell
quick stump
halcyon sand
#

Let MA and MB be tangents to (O). MCD is the secant line. Draw BK and BL perpendicular to AC and AD at K and L respectively. KL intersects CD at I. Prove that: IK = IL

#

can someone help me?

sharp ruin
dusky roost
#

for the 4 square root of 2, is it just asking for the square root of 2 multiplied by 4?

dusky roost
#

the top left thing

halcyon sand
#

wut abt it

dusky roost
#

what does it mean

#

im so confused

#

wtf does 4 squareroot 2 mean

halcyon sand
#

it means 4 multiply wit sqrt2

dusky roost
#

oh ok

#

thanks gang

#

am i cooked for my math final

halcyon sand
#

yes

#

wut grade rr u in

#

no offense

dark sparrow
#

but $4\sqrt{2}$ does \textit{mean} $4 \times \sqrt{2}$, yes.

somber coyoteBOT
#

|Ann⟩

ripe prairie
#

wait

#

so

#

2 legs on a 45 45 triangle are 4 root 2

#

and A^2 + B^2 = C^2

#

so 4 root 2 squared+ 4 root 2 squared would equal c^2

#

but the ^2 cancels out the root

#

so its 4X2+4X2= C^2

#

which means c^2 equals 16

#

but its not

#

the hypontenuse is 8

#

so why is it 8

north kindle
#

Also don’t use x as a multiplication symbol

ripe prairie
#

ik

#

i dont see a dot on my keyboard

dark sparrow
#

use *

ripe prairie
#

alr

dark sparrow
#

or \* to stop discord eating it as italics

ripe prairie
#

*

dark sparrow
#

also use sqrt() for square root

ripe prairie
#

k

dark sparrow
#

also $(4 \sqrt{2})^2 \neq 4 \cdot 2$.

somber coyoteBOT
#

|Ann⟩

ripe prairie
dark sparrow
#

$(a \cdot b)^2 \neq a \cdot (b^2)$.

somber coyoteBOT
#

|Ann⟩

ripe prairie
#

ohhhh

#

cuz the 2 squared is outside

#

alr

sharp ruin
#

Is somebody here actually available now?
Please refer to my question above

ripe prairie
#

someone help my boy

sharp ruin
#

Not gonna lie
I thought I'd get help here

#

But I have been ignored for more than 24 hrs straight

north kindle
#

No one owes you their time

sharp ruin
#

I just said I thought someone would help me
Sorry if it sounded rude

north kindle
#

Also that’s a fairly non trivial question so the number of people willing and able to help is lower than some other questions

#

I’d recommend going to a dedicated help channel, those are normally easier to get help in from my experience

sharp ruin
#

Even this channel was recommended to me by a friend of mine

north kindle
sharp ruin
#

Ohh here

#

Thanks for letting me know

dark sparrow
#

not only is it a nontrivial question

#

it's also very unclear as stated

#

you didn't tell us what data you are given about your triangle and what output you expect (coordinates of the excenter, maybe?)

sharp ruin
#

The given can be summed up in this figure
I've posted the same in the help section though

#

Do you have any idea though? @dark sparrow

dark sparrow
#

i don't really care about this enough to work anything out, so no.

trail tendon
sharp ruin
trail tendon
#

for the record im more of the first one šŸ˜‚

sharp ruin
#

Well I'm also new to geometry though

#

So maybe count me in with you too šŸ˜†

trail tendon
#

like i aint even know what an excenter is

dark sparrow
#

the center of a circle tangent to one side and the extensions of the other two.

sharp ruin
sharp ruin
trail tendon
#

when i think of geometry i think of like basic finding degrees and arc lengths of circles n stuff

#

the hard part is like all the weird things liek excenter

trail tendon
#

is this a triangle?

sharp ruin
# dark sparrow ??

It's the intersection point of the internal angle bisector of one of the angles and the external angle bisectors of the other 2

dark sparrow
dark sparrow
#

but yes excircles and excenters are defined for a triangle

sharp ruin
trail tendon
dark sparrow
#

what is your native language

trail tendon
#

english

#

i'm just bad lol

dark sparrow
#

... what other languages do you speak

trail tendon
#

i would say the only language im fluent at is english

#

i speak a little spanish ig

#

the center of a circle, tangent to one side
to me, another way of saying this
the center of a circle is tangent to one side

#

the center of a circle is a noun, tangent to one side is i guess an adjective phrase of some sort? idk grammar but the sentence doesnt make sense to me

#

;-;

dark sparrow
#

the center of [a circle which is tangent to [one side and the extensions of the other two]]

#

apologies for not making my sentences unmisinterpretable

sharp ruin
#

After thinking a lot, I've reached the result

#

It's really satisfying at the end. Not gonna lie

amber hollow
#

how am i supposed to tell when im supposed to use the angle i get and when im supposed to subtract it from 180

dark sparrow
amber hollow
#

cosine rule into sine rules

#

i mean law

dark sparrow
#

... why not just use the cosine law 3 times lol

#

you've got all 3 sides

amber hollow
#

cause the sine one is easier

dark sparrow
#

if you're using a calculator it aint much of a difference

#

but anyway

amber hollow
#

easier to make mistakes with the cosine one

dark sparrow
#

with the sine law you run into the issue that sin(180°-x) = sin(x),
so you have to know if the angle you're calculating is acute or obtuse

#

since sin^-1 will only ever give you the acute ones

amber hollow
#

oh

dark sparrow
#

and that, if you so desire, can be accomplished by comparing a^2 + b^2 with c^2 (where a and b are the sides adjacent to the angle in question and c is the 3rd side)

#

if a^2+b^2 were equal to c^2 the angle would obviously be right, bc pythagoras

#

if a^2 + b^2 < c^2 the angle is obtuse, and if a^2 + b^2 > c^2 the angle is acute.

dark sparrow
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very wrong photo.

dusky roost
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what the skibidi

dark sparrow
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since cosine law would have you calculate (a^2 + b^2 - c^2)/(2ab) anyway.

amber hollow
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so long story short, use the cosine rule if i have 3 sides unless i can clearly tell if the angles are obtuse or acute at least

dark sparrow
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nothing wrong with just always using the cosine rule if you have 3 sides.