#geometry-and-trigonometry
1 messages · Page 262 of 1
yeah, that looks better
anyway, consider making a change of variables
what do you mean
or rotate your coordinate system
i have learnt none of these
are there any worked examples you have access to of problems like this
bc if you can't do changes of variables then i don't think this is possible at all
well it amounts to a bunch of algebra
ah i see
idk how many lines
but if i was held at gunpoint for a line count, i'd say no more than 20 for all
i have a similar problem
but the focus is given
focus point
i cannot even do that one
another with the directrix
another with the equation but only asks for thr latus rectum
but this one, if i knew this one, I could've done all of them
half of 94° i assume
they face the same arc so yeah should be 70
tysm

thats the standard form of the equation for a circle
Ohhhh
Anyone here with knowledge in algebraic topology?
no why?
ah dw then
@inland kiln do you know completing the square for the quadratics?
No never heard of the term
someone help me with this?
@tame field this channel is occupied.
ok
It’s basically the idea of grouping the “x/y” terms together to form a nice square identity
@inland kiln https://youtu.be/WrH1Z-SuhhQ
Learn how to solve quadratic equations by completing the square. When solving a quadratic equation by completing the square, we first take the constant term to the other side of the equation and create a perfect square trinomial with the quadratic term and the linear term.
Th...
found the solution but idk how i did it lmao so ima just let the other dude explain
thats also what i have yeah
good shit bro
I’m doing hw rn. Idk how to start the problem at all he never really taught us. Can someone help me please)
look up tangent-secant theorem
Thank u!
The whole green shape?
Yeah
I'm sorry in advance if this doesn't help; but you could try to use the perimeter formula 4a. Multiply 44 by 4. 4 sides.
Or are you meant to use trigonometry ?
Looks like a rhombus to me
True
anyway, assuming its a parallelogram (since that's reasonable)
use trig to find the length of the slant edge
Think its cosine
try not to spread misinformation
Sorry I'm a bit rusty
you can but then you would need to use 60 instead of 30
Well why to assume its a parallelogram ?
@silent plank
if its a parallelogram ur answer will be 164 @Nikolas#3331
can somoene help me reald quizk
please
can someone help me find the surface area
ok
@silver radish do you know the formula for the volume of a cylinder?
Find the hight
ok I understand it now
volume = base * height
all you have to do is use tan and find the height
you already know the base
Try making a triangle where the hypotenuse is AB. You can use a trig function to find the missing side. After finding that side imagine pushing the cylinder back upright. Then just plug in the values you have
@silver radish
perhaps
What is your question, trying to find h?
Are we assuming they are parallelograms?
@raw tiger yes
@pastel zenith if <a and <b have equal measures, and <c has a measure 8 less than each of those, than could you set up an equation with that information, given that the interior angles of a triangle always add to 180?
kayden only 2 of the angles are equal
in daemons picture
yeah I misread that
np
@pastel zenith you could start by letting angles <a and <b equal y, and then work from there
So c is 8 less than both combined?
What formula would I use to solve this?
Ok that is what is was Herron wrong i was doin it where c was less than both
@unreal nest The first thing I would do is solve for the missing side of the triangle with the dotted line. The you know the length of all the sides of the triangle so you can find the angles of that triangles. From there you can start filling in the sizes of the angles in the parallelogram. Hope this gives you a good start
@compact spire
np
@unreal nest if you know the Area you just solve solve for the height, A=bh so h=A/b
@acoustic jungle square root to find h?
Sorry let me just verify that this is true
or false
ok it is false
that is not correct
so I don't know if it's supposed to be this complicated
but I have this
,rotate
Nice music
I'm 98% sure this is correct. but there might be an easier way.
@unreal nest
yes @acoustic jungle
I’m not sure what you got
h=sqrt 51.84
ok?
This?
Yes.
yes
You can use similar triangles
I am so stupid
can co interior angles prove lines are parallel?
You can use Pythagorean theorem to fine AE
Then say that the smaller triangle is similar to the larger triangle
I’m finding line h
I’ll let you know if it’s 7.2
yep
I also did it right my way
the complicated one
but it's easier to do it similar triangles
Then find the length of A to B and subtract that by 6.5 and then use Pythagorean theorem again to find h
$6/h = 6.5/7.8$
Fishraider:
God gamer AEP is already similar to that triangle you don't need to separate it
What point is P?
top right
Yeah you could also do that I guess
But they both work
Godgamer, yes, that works but finding BE takes effort.
You could use area to find BE, but it's much simplier knowing that those are already similar
Similar triangles again.
@unreal nest you would use similar triangles
Is it given that they are parallel?
We’re doing 3D stuff
what grade is it
9th
yeah Canadian education is stupid
same thing basically
The formula for volume of a pyramid is v= one third times area of base times area of height
what question is hard?
@acoustic jungle I have no idea what similar triangles means
Volume*
ok you should search that up
well what is half the volume?
Half the volume is 1000/6
or 500/3
Yeah
that also would be a pyramid
which sides that are proportional to the larger pyramid
Yeah
The base of the top half times the height of the top half is 500
The area of the base*
Yes
it seems like the base length is equal to the height
Yeah
WOAH
so the base area would be height squared
So the new height would be cubed root of 500
So to find the difference
It is
10- cubed root of 500
Ok
yall green how come when i asked for help no one helped me but when someone else ask they get instant assistance
ask again
I’ll help @coral zealot
could be the helpers didn't see you at the right time
I am pretty sure someone asked you if you know the formula for area and surface area of a cone
that is what you will need
Surface area of a cone
@coral zealot imagine slicing the cone up by cutting a line from the apex to the base, what would you end up with?
intuitively it's a flat shape, but what sort of flat shape?
you can try drawing lines from the apex to the base as well as circles at different heights to figure out
how does one go about solving $\sin(x)-.15x=0$?
Jeffrey:
are those $x-5$ and $x+5$?
Jeffrey:
@crisp phoenix
Guys can rectangular form look like: 3-2i or does it always have to be positive sign
not exactly certain, but i'd imagine so because i remember writing that and it's the same as 3+(-2i)
Think of it as 3 + (-2)i
also @crisp phoenix https://www.youtube.com/watch?v=qhtOBRIEPXc
Learn how to solve problems with secant lines. A secant line is a line that intersects a circle at exactly 2 points in contrast to a tangent line which is a line that touches a circle at exactly one point.
When two secant lines intersect, then the product of the length of th...
that should answer your question
Thx u
wow a section i can actually answer questions in XD
@bitter moon Jeffrey is the best!
uwu
uwu
uwu
Is angle y and x the same?
what do you think?
Idk
do you know your circle geo theorems?
could one of them be applied here.
theorem 3?
circle theorem 3
what's the name?
nobody fucking knows what you mean by theorem 3
nobody knows which theorem is numbered 3 in your particular course
Or the whole thing, like you can take a photo or something @visual mist
So it's a question about tangents and circles
yes
Which question do you not understand?
f
?
I don’t really know where to start
guys is there a relationship between sphere's volume and a cone's surface area
yo
@visual mist try to divide into triangles
wdym
In the area of the angle given
Like
Where they give you the angle
Try to form triangles with that angle
Do you follow me?
not really
Hmm
With the angle given, try to form a triangle, which has at least one of the 3 angles, the one you are given, 117°
which one
The final one
the one the two tangent makes?
The big one with alpha
oh uh isosceles?
Umm
I was thinking to make to equal triangles again on the sides
But i think that goes nowhere
Wait
ok
You know those angles are 90 degrees
and you use the inscribed angle theorem to find out that is 234 degrees, so the center point is 360-117*2 degrees
and the center point + 90 + 90 + theta = 360
@visual mist
also if you don't understand give me a diagram with points.
I don't have any points
Oh wait
The center angle is 360-117*2
and the center angle + theta + 90 + 90 =360 because quadrilateral
wouldnt the centre be 117*2
are you referring to the major/reflex or minor angle?
what's with all these triangles
Major arc AB is 117*2
ADB = 360 - 117*2
angle DAX= angle DBX=90
Major arc AB is 117'2 is bc of the theorem?
- for multiplication (not ')
because of inscribed angle theorem
@silent plank is my thing correct
your images?
No, this
Isn't phi equal to 31'5? Bc 180=117+2*phi
@upper karma
According to my last drawing
no
Why
you made some bad assumptions
You mean there isnt enough info to see that phi is twice?
wdym by phi is twice?
Like 2phi
Is it a wrong assumption to make both sides of 117 angle, to be the same angle?
The phi angles are the side ones
@silent plank
oo look an icecream cone!
how do you "know" though
@silent plank its used in my country
Look
Like this???
@visual mist
Oh
Is this wrong
yes its wrong
Oh
Lol
My bad
So there is not enough info to determine that they are isosceles
@silent plank
correct. and that has 0 effect on how the problem is solved
Lol
So can be only solved using the theorem
Lol i didnt know of that theorem
@silent plank
So can be only solved using the theorem
?
no, there are other theorem(s) that can be applied
such as angle in alternate segment, angle sum on a line, with a triangle that IS actually isosceles
how did you arrive at 90°
the green line would have a length of 28m
and there are various methods you could use
splitting it into 2 smaller triangles, w/ pythag to determine the altitiude
trig
heron's
are some that could be applied here
which one would be easier
depends which of those you know and are most comfortable with using
first off those pings dont work
imaging pinging the whole server
secondly, do you know what:
- a circumcircle means
- an internal bisector means
Yeah I know
so given triangle ABC
and you have the circumcircle Ω for triangle ABC
the internal bisectors of angles A, B, C intersect Ω at A1, B1 C1, respectively
you following along so far?
Yeah
so a1, b1, c1 make a triangle
the internal bisectors of angles A1, B1, C1 intersect Ω at A2, B2, C2, respectively
then that forms another triangle
K
and we know that the smallest angle of triangle ABC is 40deg
Yeah
so we need to find the magnitude of the smallest angle of triangle A2B2C2
do you know what magnitude is
Well come to the point pls
well i just laid out the steps to find the answer
I hv come through these but couldn't really think any further
did you draw it out
If y=4, then s=(1;0), k=0, and a=0°
If x=-8, then s=(0;-1), k=-1, and a=-45°
Are my assumptions right?
I assumed that the lines don't coincide
No, two different graphs
Book says that in the case of x=-8 there is no k and a=90°, but i think it's a printing error. Can you confirm?
Is there a formula or property I can use to solve this?
yes. properties of parallelograms
Sorry my b
ig a better question would be
what's the value of AE and which property am I missing?
look up the properties.
there's a concise list
note that the values in the diagram aren't entirely accurate. (a few errors from rounding)
yes
Thanks mate!
hello is this the right adress to ask for help with accelerated movement of an object?
When using this formula, if I need to find the SinA for ex. after I solve for SinA I need to apply Sin^-1?
What I got so far is SinA = Sin25 * 23 / 12
@inner cave try one of the #❓how-to-get-help channels
the SinA will be whatever is on the right of the equation
the angle A will be what you get after applying the inverse sin function
@junior thunder tan
What degree should the calculator be @acoustic jungle
you need to find the height of the first triangle on top, then find the height of the bottom one and add the mup
@foggy iron just type 8788 * pi/3 in your calculator and round it
Should it be in DEG?
@grave fulcrum I'm not sure the properties for trapzoid, but if you got exercise 24 by doing (57+76)/2, you can do 25 by (10+AB)/2=7
it should be in degree mode yes
Thank you
Hello guys sorry to bother you
Does someone have the time to take a look at this
Is that in a different language?
@upper karma
Yes
The first one (18) u need to find how much is sin4α+cos4αcotg2α, IF tg2α=4
The second (19) and the third (20) u need only to simplify
whoever wrote this is so bad
sin sin (x)
sin^2 (x) ??
cos cos (x)
wth
@upper karma are you supposed to just write is simply like sin (4x)+cos(4x)/4 or do you have to expand it out
I guess sin sin = sin ^ 2
Thanks man!
i need math problems that involve pythagorean thm 😔
missed opportunity for lmgtfy link
true 😔
what
lmgtfy stands for "let me google that for you"
oh
im sorry 😔
i was lookng for lharder problems that in some way incorporate the pythagorean thm but i cant find any
have you tried googling "hard Pythagoras questions"
here i'll give you a hard pythagoras question
in what city was he born and in what year
probably the 60's
nah today's actually his tenth birthday
yeah ikr
@lyric summit do you have a textbook to do problems from?
@upper karma can't help you with a question if you never ask it
Ok
so my question was
For example
Lets say
you have to find tan(135) degrees
w/out a calc
you would draw it on a coordinate plane
and then use the reference angle (45 degrees)
to make a 45-45-90
and then use the unit circle to map out the lengths for that triangle
and then find the tangent
but its weird to me that you use the reference angle
to make those ratios
how does 45 degrees correlate to 135
besides being supplementary
do u know how to find the radius based on that eqn?
Anybody got good recommendations for geometry books?
There's no geometry section in #books-old
sucks dick
?
...
i need more math problems
can you give an example of the type of problem?
which one?
how do i do 6, wouldn't it be diameter if it goes to the middle?
it doesnt mean the chord passes through the centre of the circle, its asking about the chord's distance from the centre
oh im dumb lmao thanks
dw i thought the same thing when i saw the question
w8 but how do i solve it doe
cause i have only one smaller side
which is the 8 bisected from 16
because like if it were it wouldnt be in the circle
and the 8cm one is a tangent not a chord, i think. not too familiar with circle geometry
8cm is tangent yes
is there any way beside the one where i will have to solve for line AB and then solve for B from the two line equations to solve for the coords of B?
you can use a formula to find the perpendicular distance from a point and a line
ah man
that makes it even complex
i was looking for an one liner of some sort...
thanks, though
nope
the coords of B
the ax+by+c line is given
and the coords of A is given
i need to find the coords of B when AB is perpendicular on the line
ah ok
i know i can do so by finding the AB line equations
ans then solving for x, y using both line equations
but i was looking for a more compact method
hey um, I kinda need some help with this equation, I can't really figure out a way to solve it, other than just expressing everything through x and then solving for x, which is already looking super difficult
$a_{k} = -sin(x)
a_{k+1} = 4sin(x)ctg(2x)
a_{k+2} = cos(x)
a_{7} = \frac{1}{5}$
Behemoth:
hey um, I kinda need some help with this equation, I can't really figure out a way to solve it, other than just expressing everything through x and then solving for x, which is already looking super difficult
$a_{k} = -sin(x)
a_{k+1} = 4sin(x)ctg(2x)
a_{k+2} = cos(x)
a_{7} = \frac{1}{5}$
```Compile error! Output:
! Missing $ inserted.
<inserted text>
$
l.57
I've inserted a begin-math/end-math symbol since I think
you left one out. Proceed, with fingers crossed.
this isn't an equation
equation system** yeah my bad
this looks like an incomplete problem statement
do you have a screenshot or something
yeah, but it's in Russian, I'll translate it real quick...
i speak russian
а, так это арифметическая прогрессия
да, я поэтому и записал формулы, думал с помощью них как-то надо)
why is the period of -3sin-3x pi/3 instead of 2pi/-3?
@viscid ginkgo this channel is occupied, please move!
из того, что ты записал ранее, не было понятно, что речь идет именно об арифметической прогресии, если что
а так, наверное надо не морочить себе голову и просто записать уравнение, гласящее, что разности соседних сленов совпадают
то есть $\cos(x) - 4\sin(x)\cot(2x) = 4\sin(x)\cot(2x) + \sin(x)$
Ann:
решить его все равно придется, т.к. спрашивается значение x
а когда уже его решишь, найти k не так уж и сложно
ага, понял
Спасибо 🙂
somebody please help
i have an assignment due in 20 minutes and i don't understand remaining problems
👍
and you decided not to even post it, wasting 10 min of your own time?
use secant theorem for the first one
and intersecting chord theorem for the second
you do have access to a list of circle theorems right?
i'm more concerned about why you're doing these questions without the required knowledge
do a quick search on circle geo theorems
and then match which theorem is applicable
is probable more efficient than me explaining from scractch here
no you need to know circle stuff
So xD and BA are two secants that intersect at point C
right
Rip so it's not secant theorem?
||BA isn't a secant either||
use < >
These articles seem useful.
instead of deleting the http
Oh okay
Huh cool didnt know that.
OOoh wait
Maybe
Btw I'm trying that last image.
CB * CA = CD * CD
yes
Meaning: 9 * 12 = x^2
Damn thats easy
lol
Cool theorem tho.
I guess its same idea for the 1st image too.
@silent plank why you not answering my dm's
because i prefer not to answer in dms,
and you weren't entirely specific with your request
Okay
I repeat my question
Could you give me a clear example where C is "shift up" (as you said) and SC and ST aren't equal?
@silent plank
(Sorry for the last tag)
that is the example
also did you mean CT and CS
Yeah
just move the point C a bit higher on the circumference
like maybe extremely close to point T
and its extremely obvious that CT and CS aren't equal
But in the problem he showed it was really clear that TC and TS were equal lol
Oh
If O is the middle of the circle CT or CS.
Yeah
This doesnt' mean TC and TS are equal. though.
No
There may be cases where TC and TS are equal
If C
But if it is CS, CT and TS must all be equal.
Meaning it will be equilateral triangle in circle.
But HOW can we exactly know that the problem wants us to go through that assumption (that CS, ST and CT are equal?
Is there any key in the question that may give it to us?
From the image, I would assume TS and TC are not equal
But I haven't seen the question so idk.
I would
TS was a typo
Well yeah
probably
But
But HOW can we exactly know that the problem wants us to go through that assumption (that CS, ST and CT are equal?
@upper karma
if the given diagram doesn't explicitly give certain properties, try not to assume anything
CT = CS when O is center of circle and OP is angle bisector
IF it lies on PO and PT and PS are tangents
If O is the center CT and CS are guaranteed to be equal.
From the image it looks like CT and CS are equal.
if O is the center and that's all we're given, we can't assume ct and cs are equal
because we dont know that OP is an angle bisector
it looks like one, but we can't assume that it is
well it is actually reasonable to assume that PT and PS are tangent
I have definitely got to see a bunch of geometry theorems
then again, it's not given that they're tangent
and from theorems etc, PO would actually be an angle bisector
however, lets make a small adjustment to that image by removing that line PO
like i said, reasonable assumption based on the context
now, if line PO was removed, you have no helpful information about where C actually is (other than its on the circle)
Then TO and ST are probably the same.
probably?
I would assume it is given O is in the center
Yeah, discords being weird for me rn
discord has been shitting itself every week
OS = OT, PS = PT are all you can gather
Yeah
usually you arent to assume things that have its own designated symbol
like the right angle, same length, parallel
tangent line is not one of them so you can at least comfortably assume that
just ask
is the answer to this problem 3+root57 over 2
,w solve -2x^2+6x+24=0
thank u
ok
ok owo
UwU
The angle θ=π6 is in standard position and has a terminal side that coincides with the graph of a proportional relationship represented by y=kx.
so angle theta is 30 degrees
Do I make a 30,60,90 triangle
and see what points that lines up on?
or
do cos30, sin30 = x,y
becuase my math teacher said (cos theta, sin theta) = (x,y)
if its on the unit circle then yes
x^2+y^2=1
It doesnt specify if its on a unit circle or not
holdup (costheta, sin theta) = (x,y) only works on the unit circle?
yah
at the point (0,0) if u connect the orgin to any point on teh circucfrence (x,y)
that angle formed
sin of that angle is the y coordinate
and cos is the x coordinate
Yaaa
holdup
so lets say i have circle O where O is the origin (0,0) and circle O has radius 1
x^2+y^2=1
and the point (1,0) is point B on the circle
mhm
lets say we have a random point on the circumfrence A
angle AOB=30
ya
sin 30 is the y coordinate of of A
and cos 30 is the x coordnate of A
The angle θ=π6 is in standard position and has a terminal side that coincides with the graph of a proportional relationship represented by y=kx.
how bout for that question
specifcally
im guessing we dont use the unit circle
no but it still works for any circle
a. Find the constant of proportionality, k.
k=
angle θ = 360 degrees
so lets say we have (x-a)^2+(y-b)^2=r^2
awh shit its just 0
yah
pi=2xpi for any radian
what happens if the angle was 30 degrees
how would i approach that problem
well theres 2 ways
if its ust a generallity problem
use WLOG
whats WLOG
without loss of generality
meaning we just say a length or something is a number
so if we assume the origin is (0,0)
actually
here
let (a,b) be the origin of a circle
ok
and r be that radius
ya
so a+rcos30 is the x coordinate
and b+rsin30 is the y coordinate
bc
the origin is at (a,b)
can u voice call
and the rightmost point of the circle is (a+r,b)
no
k
i was just gonna make
a 30,60,90 triangle
hmm do you now the radius
find the point
being
root 3, 1
and the origin of the circle
nope
do u know the coordinate where the 30 degree angel is made
nope
literally
all it says
it only says the radius?
The angle θ=π/6 is in standard position and has a terminal side that coincides with the graph of a proportional relationship represented by y=kx.
a. Find the constant of proportionality, k.
k=
the angle is actually 30 degrees
my bad
OHH its not 6*pi
ya
k
my copy paste
fucked up
because it cant copy the divide sign
actually do you now tan
tangent
yeah i can do tangent
like sinx/cosx=tanx
well tan is just the slope of the line
no
i didnt know that lmao
so sin30/cos30?
yah
that makes sense
because if this was on a unit circle
that'd find the slope
it could work on any circle
but its more coplicated
thats why we use unit circle bc it has the easiest coordinates to work with
the origin is at (0,0)
and all the intercepts have a 0
and the radius is 1
k but theres a general way to do it though
if u have any circle cenetered at (a,b)
and the radius is r
and theres a point on the circle (c,d)
the angle from the point (a+r,b),(a,b),(c,d) is x
then c=a+rcosx
and d=b+rsinx
ok tyy
I need help with part b of this
In part a I found the big hexagon area and so far in b I found small hexagon area
do you know about 30 60 90 triangle?
Yeah we learned that but the only value we have is x
Is it still doable with just x
yah
How
because if we let the length of the small hexagon be x
then root(3)*x/2 is the apothe
apothem
SCP can u help me with one more question after
k
ty
So what do you mean let it be the length of the hexagon
Do you mean like x is side length
yah
Okay I’ll try again thanks
Write an arithmetic sequence that gives the nth positive x-intercept of the graph of f(x)=cos1/8x. Leave your answer in terms of π.
k theres only 2 places where it hits the x intercepts
in one rotation
0 and pi
so its just pi(n-1)
because the period is 2pi
for every 2 rotations it touches the x int right
oh wait
It's 1/8 or 18
Cos x/8 right?
well in that case its just the same thing but it muliplys by 8 each time
yea cos x/8
0+8pi+16pi...
isnt every nth positive x intercept
just
+8pi
yea
it is
yah thats the domain
so should I say
8pi(n) - 4pi
Used general solution
k u have the function f(x)=cos(x/8)
using the winding function
the positive x intercept
will always any multiple of 2pi
bc pi and 3pi and 5pi... and so on
have a negative x inetcept
the answer is
4pi(2n-1)
right
assuming n=1
Yaa..
kk
So back from earlier should my equation look like this
Question??
@upper karma sure
Yes
Okay
So I’m pretty sure we have to use the apothem formula where: Area=1/2(Permiter)(Apothem)
yah
Okay thank you
Cool


