#geometry-and-trigonometry
1 messages · Page 260 of 1
subtract that number from 180
but one of the solutions in an answer was subtracting from the bottom number?
Always use the positive ratio for reference
im sorry if im really unclear
o
so we are starting with positive ratios first
ok
And then use the table or the picture I gave you to Solve it
ok
That's how we do it :D
Sure
Pick the positive ratio for reference :)
so i got 104.9988703 from arcos(-.2588
then according to the graph
im supposed to add it?
which means it is 284.9988 but thats not in the 3rd
quad
Positive one, which means you put 0.2588 instead of -0.2588 in your calculator
Always pick the positive ratio for reference
so
it doesnt matter what the ratio is
just make it positive
so answer is 255.0011?
ok
so
i think i get it
for quad 3
for cos and sin
u add 180 to it
but if its tan
u subtract from 270?
and for quad 2, u add 90 to the angle for cos and tan but subtract the angle from 180 if its sin
According to that graphy table, there should not be 270 plus or minus something
and for quad 2, u add 90 to the angle for cos and tan but subtract the angle from 180 if its sin
@dull remnant
Nor 90 plus or minus something
ok
lemme try again
for third quadrant, for cosine and tangent, you add 180 to the angle, but if it's tangent you ?
for the second quadrant, for cos and tangent you subtract the angle from 180, but for sin you ?
for the fourth quadrant for sin and tan you subtract the angle from 360, but for cos you ?
i dont know what goes in the ?
Stays the same
q1, no change
Q2, 180-theta
Q3, 180+theta
Q4, 360-theta or just -theta
what
for all of them?
but there is a sign
after the equal sign thats negative for sin and cos in quad 3
That means
The ratio
If the ratio is negative blah blah blah
Sine is positive for Q1,2
Cosine is positive for Q1,4
Tangent is positive for Q1,3
@dusky surge OO
so at the END once u get the angle from 180-theta
then u change the positive or negative sign
depending on the stats
wait thatwouldnt work because if the angle is from 180-270 you cant change the sign right?
wait thatwouldnt work because if the angle is from 180-270 you cant change the sign right?
@dull remnant
Hmmmm..... I don't really get what ya mean, do you have an example
ok
im just confused
on why the 180+theta
applies for everything in q2
because in the graph
it says sin stays positive
but tan and cosine dont?
yea
ok
so lets say
i get a problem
that restricts to q3
ik its 180+theta
for all of them
would that work for all of them?
because in q3 tan seems to be psotive
Yep, you're right, so when you get something like arctan(1) on Q3, we will have to first find the 45° then apply 180°+45° to find the answer
It does something when you are NOT calculating the inverse trigonometric function
It's another big topic XD
ok
sure
alr
to finish the question
if the ratio is positive
u just enter in calc, and then do whatever the quadrant says
what if the ratio is negative?
Find the angle for positive ratio for reference.
i just turn it positive?
Do it in the draft.
wha tdoes that mean
Like for
sinθ=-√2/2 on Q3
Since for arcsin(√2/2)=45°
The answer will be 180°+45°
It means, we do not TURN it into positive, we just use the positive ratio FOR REFERENCE
ok
so for sin theta=-.45 on q3
arcsin(.45)=26.743
so 180+26.742=206.743
so that would be the answer?
The length of a chord is equal to its distance to the center of the circle. A second chord in the same circle is twice as long as the first one. How far is the second chord from the center.
Correct! @dull remnant

that sintheta=.45 and sintheta=-.45 are the same?
Nope
One is positive one is negative XD
how do u do this The length of a chord is equal to its distance to the center of the circle. A second chord in the same circle is twice as long as the first one. How far is the second chord from the center.

The positive one is on Q1,2
The negative one is on Q3,4
@daring venture please use the questions channel :)
ok
@dusky surge ok tysm for answering all of the questions
You're welcome!
sin(x)=/=x
,w sin(0.01 deg)
,w sin(0 deg)
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,w sin(1°)
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,w sin(1°)
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,w sin(1)
Sounds like we got an engineer
How do I tell what these signs should be if they are plus or minus? Is it just flipped? If cos(x+y), then cosxcosy - sinxsiny ?
Yes
I think the reason i struggle mostly in math is because there is so many small things like this that my trash teachers failed to teach me
<+ on left corresponds to - on right and vice versa>
aight
what have you tried?
this is an identity
that is cos(x/2)
so why does it can't plug 106 into x?
otherwise i am just not sure where to start solving this one
,w (1+cos(106 deg))/2 = cos(106/2 deg)
which specific identity were you trying to apply?
whoops forgot the sqrt
,w sqrt((1+cos(106 deg))/2) = cos(106/2 deg)
you should be able to
oi vey
it was right it just didnt want it like that
it's asking for an exact value as a degree and yet the answer was cos53
thanks
anyone help
what are you asked for
@tame ore f(x) is plotted on the y-axis, so where is the line in the negative part of the y-axis? (f(x)<0 implies that f(x) is negative, right)
ok so
- why did it take you 45 minutes to answer that
- what's giving you trouble as far as finding angle ABC goes
i have the coordinates of 1
i have the coordinates of 2
i have the distance x between the 2 coordinates
what's a formula i can use to calculate the coordinates of all 5 points of the star?
@hushed bison construct coordinate axes
Let point 1 be at the origin
Let the x axis go through the right most point
i dont study math, this is for a cs assignment
im looking for a formula
@hushed bison are you fine with polar coordinates
Trying to find solutions of sin and the like but I got an imaginary number
Why not lol
because i dont study math
i study computer science
i just need a formula so i can write it into my program
Lσνιηg✧Sσνєяєιgη:
$\cos^{2}y \neq 1-2\sin^{2}y$
Lσνιηg✧Sσνєяєιgη:
need a formula that can calculate all 5 vertices with the given information
Do u need exact answers or approximations
exact coordinates
$\implies (\sin{y}-1)(3\sin{y}-2)=0$
Lσνιηg✧Sσνєяєιgη:
@tropic tide
Oh, I got confused with double angle lol
no substitution is being made here
well whatever this process is called
I'm having trouble finding the horizontal shift of a cosine graph that's shifted -3pi/8 to the left from 0, ends at 5pi/8 so it's a cycle (or period?) of pi. The horizontal shift is apparently 3pi/4 and idk how
I tried doing 0 <= 2x - 3pi/8 <= pi (and 2pi)
but that's wrong
gets me -3pi/16 <= x <= 5pi/8...
<@&286206848099549185>
how do you get C when this graph is
-3cos(2x+3pi/4)
C?
3pi/4
it's C right?
-Acos(Bx+C) + d
I believe it is
I'm supposed to get the equation from the graph
hm
one way is, you have 4 known points by looking at the graph, you can make 4 equations and solve for a,b,c,d but this is a long method
What do you get from: (cos(20°)/cos(10°)) - cos(10°).
I get -sin(10°)^2
should be -sin(10)^2 / cos(10)
Hmm. I did = (cos(10°)^2 - sin(10°)^2)/cos(10°) - cos(10°) = cos(10°) - sin(10°)^2 - cos(10°) = -sin(10°)^2
Is there a link to the bot script so i can illustrate?
you're forgetting about the denominator of sin(10)^2
damn no one can help me with my problem I've been stuck on for 1 hour
Ok. I got it. It's -sin(10°)tan(10°)
Pretty confusing graph for 31 not sure where you find amplitude at
Or vertical shift
I know it's -3-3sin2x but it's a weird graph ends in a weird way
I see it intercepts at -3
can't tell if that's vertical shift or amplitude
and apparently 33 has a vertical shift of 3 now that's not intuitive
amplitude is 3 since the graph is shifted down 3 units (so the line "about" which the values of y fluctuate is -3)
graph touches the x-axis at its peak aka goes up 3 at most
shifted down because theres a -3 outside of the sin() stuff
isnt vertical shift the moved down part or am i dumb
@viscid ginkgo can you wait 10min? ill try explaining it better when im on pc
ok
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yeah but I'm getting the equation from the graph idk if I'm misinterpreting
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I just didn't know where the amplitude is found
and where you find the vertical shift
since they're both the same number
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and vertical shift lol
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chapter is "Get equation from the graph"
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so I'm looking at the graph and finding the properties of the graph
well I have the answer from the back of the book
but I want to find it out myself
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that's B you get it from the cycle = 2pi/B
so pi = 2pi/B but
it's actually 3-3sin2x - pi/2
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yeah I still don't know hwo to find amplitude and vertical shift from that graph
spent like an hour on it
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yeah
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like the wave goes half way
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idk about amplitude though
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well like the wave goes from -3 to 3 for example
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yeah
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and I think the graphi is reflected about the x-axis whatever that means exactly
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I think I read that sin equals cos when it's negative or someshit like that
lool
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well it's upside down
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you see it points upwards when negative amplitude
and starts from the bottom when positive amplitude
"baseline" sine I guess that's how I'm gonna think about it
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yeah, thank you
@scenic scroll if EAF is 45° what does that tell you about the two angles around it
If the whole angle of that rectangle is 90°
Maybe you can use letters instead of numerical values?
@scenic scroll think about the angle that you are given, and look that there are two equal triangles
And that they are inside a 90° corner
Can someone help me with this?
no
isoceles is what again? (not native
)
ok
and yeah drawing is a must
wtf do you mean "tf"
@vale nimbus its a triangle with 2 sides of the same length
@bitter jetty have you drawn it
im tryin
I was helping lol
wdym?
bro i asked what an isoceles triangle is 😭 ur tripping
no worries :p
If O is the center of the circle and M is a point then the circle equation will be MO = ... right?
i cant seem to draw it
MO = ...?
i'd just draw the triangle and then draw a circle around it
how do i
Like
it only gave me endpoints for the inscribed traingle
Yes
they pretty much gave you the lenght for the hypotheneus
MO = the rayon of the circle
Have you drawn the axis
no
@vale nimbus dudeee
how do I
i just gave him a hint?
o
Uggh
ima just go back to anime man ur 
o ya i have that
Okay sorry its rotated lol
im drawing it on there rn
Have you drawn the line of the hypothenuse
yes
P(4,4)
the radius is root(32)
Okay I just saw what a circle equation looks like
It tells us that the hypothenuse ...
no it isnt
im confused
wth is MO=r
So (x, y) , what does x mean in a parenthesis like these
We want that all the points of the circle has the same distance with the center
how much u move on the x axis
@upper karma ik that
@upper karma just let al3dium explain he's doing a good job

I would gave a better explanation in French...
je m'excuse 
So if you know that its moving 4 to the right and 4 up
so from the origin to (4,4) that's the radius right
is it?
so the length of the hypotenuse is sqroot(32)
The radius its 4
I wanted him to say length and then get some coordinate geometry things
no it isnt is it?
But ig its same
cuz they didnt say the center of the circle is the origin
so how do u get the length of the radius
@upper karma can i say how i'd do this?
Yes
@bitter jetty it is the length
Of the radius
Do you know the distance formula
Wth is the hypotenuse of an isocele triangle?
so sqr root 32
That's why i wanted this
draw a line from the origin to P(4,4)
draw a line from the origin to Q(0,4)
draw a line from Q(0,4) to S(4,4)
now u have ur triangle
construct a circle around the triangle
measure how long the radius is
or calculate the radius if it isnt easily measurable
@bitter jetty yeah
u could also make Q have cords (4,0) and do the same thing
I dont know what piece is doing lol
Oh the triangle is also right
isoceles in a circle
how exactly are any of these sides the radius?
its not given that the center of the circle is on the hypotheneus either
yes
Lol
XDD
the triangle aint right is it??
im being trolled heavy as fuck
@upper karma who knows maybe it looks like this even?
the sqrt(32) thing is the lenght of the hypotheneus
which can never be the radius of the circle since both ends of it have to touch the circle
at most it'd be the diameter
Actually the triangle is right
Yes
Yes
yes
pretty sure u can solve with area of a triangle in function of sin or whatever
@upper karma okay
Did you saw my post?
I tried to set litteral values then solve an equation
Yes I saw it
I feel so dumb
I didn't
oh.
I tried to solve an equation but that don't work
it seems so tedious to solve wtf
if there is no big brain way to solve it and requires 10 different equations then it is not a very good question
also @upper karma my bad i was wrong the radius is 4
maybe there is a less tedious way to solve it
well not really tedious just
i cant actually draw the problem down on my paper properly
so thats tedious xd
Geometry sucks
geometry is intuitive though
Okay so
First
Calculate the third side of the violet triangle
@bitter jetty yeah, get the AC
ok
What you got
1.89
Okay so
?
Hmm
Okay, so draw a perpendicular line from C
(I haven't tried this so, i might be wrong)
ok?
Have you drawn it
yes
Okay so draw this, continue from C a line until the end of the violet triangle, so you get rectangular triangle
u mean a triangle inside a recatngle
Sorry, from C, draw a line to the right
And stop when it gets to the perpendicular of the vortex of the violet triangle
i have be and af
no sry
Idc if its horribly drawn
im on computer
Oh
i dont have a phone
wait let me see
di u get the idea
sry lines arent straight
idk
Look at AF
its 3.04 - cb
= ba
that doesnt rly help tho...
yes kinda
See how it helped
@upper karma did u check my solution 
No xD
then why'd you wanna see it dafuq
Im dealing with this first
its not a system
@vale nimbus bc i thought i wouldnt be able to do it first lol
@bitter jetty why not
What
Nonl
Sorry
Try doing pythagorian theorem
Idk if its written like that lol
With both triangles
With ABC and CEF
hold on let me try using law of cosines
Oh
sins*
ok so for ba i got 1.48 and for bc i got 1.18
does that seem righ
ok i think it is
this one is confusing
ive been working on it for like over 30 min
@bitter jetty how are you going to use law of sin when only 1 angle is given?
@vale nimbus idk what that is so
a/sin(A) = b/sin(B) = c/sin(C)
i used it to find the angles for acf and then i did it for abc
@bitter jetty dang this one is weird af
Oh got it
so like de = ab/2
k
i got it
this is my last q
the volume should be directly proportional to the side length right
but when i calculate it it oesnt add up
?
it would be ^3 porportional
rly
for example try similar triangles with area
lets say area of 1 triangle is 3 and the ratio between the lengths are 5
the other triangle would not have an area of 5
but rather 25
try the question and let x be the ratio
so $2x4.5x4x$
Fishraider:
then it should be pretty nice from there
i dont think so
i think its supposed to be a clean number
i got it tho
@acoustic jungle thx
@bitter jetty did you remember to cube the x
In order for sin^-1 (sin x) = x, x must be a value between () and ()
I don't really even get the question, I mean sin^-1 and sin x?
I really don't know maybe -pi/2 to pi/2
Yes that is correct
oh
It's arcsin(sinx)
Sin has a range from -1 to 1
I think you meant to say you thought arcsin(x) had a range of 2pi
which it doesn't because it then wouldn't be a function
try drawing a right triangle with PQ as its hypotenuse
then label its sides in terms of the length of ab
ping me!
@ancient jacinth i want you to draw a picture of the complete circle
i just did.
send a pic
you know what to do?
intersecting chords theorem?
yeah lol
tysm
@rich wolf cani ping you, i feel like i will have more problems in about 15 mins lol
sure
what is the formula for the area of a parallelogram
hey guys pretty new here and i have an assignment due tonight and was wondering if anyone would spare some time to help? if not its cool, im just having a tough time with this
@solid topaz just ask
its more so algebra 2 w/trig
#3
the angle is 60 degrees and i need to find the angle measure of z
wait is alright if i ask question shere instead of the question channel
@crisp patio find the other two anglws of that triangle
oh i got it figured out, thanks for helping though
amd as in advanced micro devices?
Hello peeps! 😉
I’m new to the server
May someone explain how I evaluate a logarithm of -> log (base of 10) 5
Thank you 🙂
generally you don't, you just leave it as log 5 because its irrational. sometimes it may be appropriate to use a calculator, or use some technique to estimate the value of the logarithm, but otherwise, theres no real way to evaluate it that im aware of.
@worthy oxide the hint is really the answer here
Ok
Is this the answer?
The inner term has 2 raised to power of 1/2 raised to the power i
@Cliff#0001
@Cliff#0001
Cliff you son of a beach
@worthy oxide
they left
anyone help?
what are you allowed to use?
assuming you can't simply state circle theorem(s), apply properties of isosceles triangles
||radii||
but still they intersect at different places
what intersects at different places?
the radiis
the construction of the red dotted line OC creates 2 isosceles triangles:
triangle AOC and triangle BOC right?
oh yeah i thought u were talking about the other ones
can you continue from there?
let me try
okay
Not sure if this is the right place to ask, but does anyone know if there's software that can determine the length of lines in an image, if provided with known reference points?
https://puu.sh/FrGkE/e36311a1a2.png
This is an example of something I did manually and it's something that is quite time consuming in my job, so I'm looking for a way to automate it (in the image given I knew the total height/width/length of the table and used that to roughly calculate pixel:cm ratio)
i couldn't work it outtt
30 is the right answer
assuming it's a right triangle
oh duh it is.
cosine is a nice thought, but that's adjacent over hypotenuse. Sometimes at the beginning students have trouble deciding if a leg (cause adjacent is NEVER the hypotenuse) is opposite or adjacent.
Its adjacent if the leg and the hypotenuse form the angle.
if the leg in question does not form the angle (as it is in this problem) then it's opposite. (note that for ONE angle the opposite is the adjacent for the OTHER angle. Some identities later rely on this fact.)
yup np
yes.
your friend would be right. about X and the angle in the cosine would be 60 degrees.
@visual mist
tri BOC is isosceles. determine angle OBC
then determine angle BOC
tri AOC is also isosceles. determine angle OAC
then angle AOC
what's the relation between angleBOC, angleAOC and the angleAOB?
well OBC would be x+y? and BOC would be 180-2(x+y)
OAC would be x and OCA would also be x and AOC is 180-2x
yep. just need that last part now
the relation.. let me see
they r all the same
wait no
r they? im not sure abt their relation
try not to overthink it. mark them on your diagram and it should be quite clear
you've got quite a bit of notation issues
but how did you get 59.0° for your theta'?
@leaden belfry some computer vision library maybe? I don't know of any super reliable way myself, but I'm sure something exists
mixing $\theta'$ and $\theta_2$ notation is not recommended. \
the equation: $\theta' = \text{TOA}$ \ doesn't make sense
and for some reason that $\theta_2$ became $\theta^2$ in your work.
ramonov:
no it doesn't
Its just to differentiate it from the other abgle
depending on the context its ambiguous
Like i didnt actually square it it just means second angle
and may be interpreted as $\theta \cdot \theta$
ramonov:
which is an issue
if you want to use the same variable
you should be consistent
and use subscripts for both
But what did i do wrong in my calculations
i.e. $\theta_1$ and $\theta_2$
ramonov:
ramonov:
that looks alright and is completely different from what you wrote down
Yep must have done something wierd with my calculator before
What about my second calc
same process, calculate it again.
um what's that "x" doing there?
I have no idea
dude it's not multiplication when you take a trig function of something
how are you getting that?
Very very confused
what exactly are you entering into your calculator?
dude don't use android calculator it kind of sucks. you're probably not doing order of operations right either
because the value you initially got for theta_2 was actually ok
That’s some bad luck 👎
sorry i went to shower c=a+b
nfi how you got ~70 in the previous image
He just had some bad luck that’s all
sorry i went to shower c=a+b
@visual mist
yes. now apply that to what you have in your original question
Idk im using my phone calculator its confusing compared to a normal one
okya
So 31 and 58 are the correct angles
Ya but what did you insert in ur calculatorrrr
Bro idek
Ok
not 58
no! its not
,calc 31 + 58
Result:
89
its not either of those
?
read carefully
,rotate
Umm 31 plus 58 plus 90 is 180 right? Yeah it had a few decimals but teach said round it
round consistently
Ah yes
Soz
Running on no sleep equal big stupid
Thank u for all the help aha
Yes
@visual mist not applying it properly
Thank you too
identify your smaller angles
ok
,rotate
looks alright now
im not sure what to multiply
the only two numbers in the question
ah gotchu thanks
AHKW is a cyclic quadrilateral
so everything has to add up to 360?
if by everything you mean internal angles, that would apply to all quadrilaterals
do you know any properties that are specific to quadrilaterals that are also cyclic
each pair of opposite angles = 180?
um can you write a better description
for example: m<H + m<W = 180
ok that's a bit better.
because they are opposite angles
opposite angles add up to 180°
NOT each pair IS 180
anyway, consider applying that here.
alrighty ill try--how would i get the measure of the external angles with that though?
do i divided 180 by 5 to get H?
you shouldn't need to apply external angles here
a quadrilateral has 2 pairs of opposite angles
m<H + m<W = 180
(is one of the equations you can get)
what is the other?
m<a + m<k = 180?
so should i add 8 (m<A) and 10 (m<K) and then subtract that value from 180?
no.
i can't be bothered writing the degrees.
m<A = 8m right?
(i'm expecting quick yes/no responses for these)
mhm
what's mhm?
yea, m<A does = 8m
and m<K = 10m right?
yes
can you make those substitutions into the equation:
m<a + m<k = 180
you wrote earlier?
8 + 10 = 180
where the the ms go
m<A is 8m NOT 8
m<K is 10m NOT 10
8 + 10 = 180 is clearly a false statement
my bad hecc
but ramonov don't you see that the lefthand side has a 1, and 8 and a 0 and so does the right and so they must be equal /j
1?

cmon now guys


