#geometry-and-trigonometry
1 messages · Page 343 of 1
Did u mean 11.5 ? Or 11,5
11,5 is 11.5
Alright ty
Np
Alright I solved it I got 3.9196 then I needed to round to the nearest tenth foot. And got 3.9 but it’s wrong
@olive cove
,w solve cos(11.5)=x/40
Wait let me check everything
Oh sorry it's my fault
I got confused because you wrote the 40 at the hypotenuse but it's the vertical drop
You have to use tan
,w solve tan(11.5)=40/x
Is 22.1 correct?
I just realized that Wolfram alpha uses radians as a standard so that's why it was wrong.
Yeah
Alright
But 11.5 radians is something different than degrees
Who here is good with the Pythagorean theorem

Im confused on how to solve for this. I know that we have to use Pyhthagorean theorem, But Idk how to label which side is
identify your longest side in the triangle
so we have a picture like this
We can take the base of our triangle to be the line segment connecting J and K
We know the area is base * height/2
I would try to determine the height in terms r, t for any point L
should involve finding the line orthogonal to JK
And then projecting L onto it
does that make sense?
Ping me if you have any questions shiv
oh wow thanks boss I think I know how to the problem. It's easier to draw out the problem and think of it geometrically
ill finish the problem tmr and lyk if i have any questions thank you 😋
The c should be the longest I believe
and sin is even
Not the negative sine
hm?
cos (2wt +90 - 90) = sin(2wt)
here
dont ask me why there is an omega and a W tho
I assume w=omega W?
Well omega, it's part of a formula
Was trying to just understand the trig portion on how they got neg
isolate x,
then its just a matter of entering stuff into your calculator
(in this context, you're working with degrees so make sure your calculator is set to degrees)
pls help
@modern brook when u need help with something just share it outright instead of asking first
but sure ill help if i can
thank u :))
can someone help, imma litte confused
@sleek light definition of trig functions
@modern brook as for u if ur still up what u should do is use triangle theorems to prove that the two triangles are similar
❤️❤️❤️
for the section under saying what the sinusoids on triangles are u have to use law of sines or law of cosines to prove each one
oh yeah, that's what i know but where should i start
well ED seems to be a section of AD
and DC seems to be a section of DB
and AD and DB connect
and so do ED and DC of course
which means they make the same angle at the same point
whats answer to question 1
SOHCAHTOA
What's the question?
"At what time is the water level the deepest according to $y = 2+3.5sin(\frac{\pi(t-1)}{6})? The time t, is hours after midnight. Water levels may be negative".$
Fish of the sea
I know that the lowest function value will be when the sin function = -1
i.e 1.5m (2-3.5)
after simplifying I get $-1 = sin(\frac{\pi (t-1)}{6})$
Fish of the sea
however solving this gives me t = 12n+10
the correct answer should be t = 10
it only makes sense if n = 0
is it really that n = 0 or am I missing something?
How do you graph this?
That’s the graph but I don’t understand how -11/2 graphs to that
mostly apply properties of right triangles and radii of circles
I know I learned this a while ago lol, I'll ask a specific question, how do i figure out where the line crosses
is it like 1/2 of 60 or something?
apply perpendicular chord bisection theorem (which could be justified with triangle congruence)
construct YA and/or YB
apply properties of right triangles and radii of circles
How would i do this?
i put the numbers there to try to guess
wait are AC and AB and BC equivalent?
<@&286206848099549185>
College Trig question
On my end.
how do you go from:
Cos(x) = -1/2
to
Quadrant II --> 120deg x pi/180 = 2pi/3
and finding all the other quadrants
I dont understand
Quadrant III --> 240deg x pi/180 = 4pi/3
I just dont understand how you get there
(its the reference angle topic)
and on the other side... I am at the step of Cos(x) = 1
Quadrant I --> 0
Quadrant IV --> (would be 360 but you cant include it in the equation)
it's a quadratic in disguise
$1+\frac{3}{7}$
moshill1
can someone prove it that AKC and DKC triangles are similiar triangles
Will some one have time to help me really quick
how do i do this
You know soh cah toa?
What did you try?
For which one?
X
Can you show your work?
You have to make an equation
I did Tan(30)x9.2 to get 5.3
Oh
You have to multiply both sides of the equation by x
Because you are dividing by X and not 9.2
oh ok so
Tan(30) x X
and 9.2 x X?
another answer i got for the hypotenuse was 4.6
No the equation is
tan(30)=9.2/x
Multiply both sides by x
tan(30)*x = 9.2
And then divide both sides by tan(30),
x = 9.2/tan(30)
Oh ok
And for z you use the same technique but then with sinus.
thank you
No problem
@olive cove so is it x=15.9 and z = 18.4
Is someone one is willing to help I have a question
they'll never know if they're willing to help if they don't know the question
what is the problem?
@toxic trench help?
@serene obsidian use pythagorean theorem
And also don't mention people for help unless it's the helpers mention
ur alright
ok so
i got sqrt 20
which is 4.47
and if i round to nearest 10th
4.5?
is that correct
Still
ok revised answer 15.588
height of a equilateral triangle is always a sqrt3 / 2, a being side length
$\fracf{a \sqrt{3}}{2}$
hiidostuff
Compile Error! Click the
reaction for more information.
(You may edit your message to recompile.)
hiidostuff
hiidostuff
ok here it is
K
LMAO
i got home at like 6 pm
o, wasnt paying that close of attention, then the answer is 15.6
Wait which one
the one where the area was 15.6 obviously
this one
for the problem you deleted for some reason i got x = 5.0, y=22.4, and z=11.2 might be wrong tho its been a while since ive had to solve a problem like this
@arctic mirage
I got x = 5, y = 22.4, z = 11.2
Yep
GG
This is the last one I have to do
And it’s one I have no clue
I think it’s 300 smth tho
dang i want cookie
but tirangle
oh ohhhhh
find the hypotenuse of the bottom triangle
do some trig to get the angles
find the complement of the angle between the hypotenuse and the leg thats 91 ft long
then do some triangle things
Still don’t get it :/
Ok so
I got
c = 91.38 or -91.38
Dam
91.4 ?
Is that correct
Can someone double check with me and confirm 100%
hmm
i think
sounds about right
oh so now do tan(x)= 5/91.25
do u understand why?
Last question
Identify the similar triangles here
If someone could please help me it would be greatly appreciate
What's the question?
Could someone pls help me with this? I need to find those two angles
idk how to find x but y is more easier to find:
since the whole triangle is a right triangle and there are already two given angle measures: 25 and 90. you can add them up which is 115, then subtract 180-115 because the sum of angle measures in a triangle is 180. 180-115 = 65. angle y = 65 degrees
@merry fiber
Ohh thank you so much
no prob ! 
could someone help me with this problem?
hmm
well theres a lot of identities to be used here
firstly, what is tan x equal to?
the directions only say prove the identity 😦
tbh idk, thats all the sheet says
opposite/adj.?
oooh i thought you meant in general but yeah in this prob yes
alright so now we have $\frac{\cos^2{x} - 1}{\cos{x}} = -\frac{\sin{x}}{\cos{x}}\sin{x}$
hiidostuff
so what is cos^2 x - 1?
-sin^2(x)?
hiidostuff
and i think u can see how it works from then on @dim cliff
yes i do! thank you so much!
no problem
Could someone help me with this x/tan 28 = 480-x/tan 34
This is my original problem if it will help
ABCD = rectangle, BEFG=square, then area PRC=?
yep thats all thats given
you have to find x
so anyone know how to do it?
I don’t think this works out, angle bisector theorem gets you one equation with two unknowns. I don’t see a way to find one of the unknowns, nor do I see a way to get another equation. Maybe someone else can spot sth
should i ping helpers or somthing
<@&286206848099549185> does anyone know how to do this
you have to find x
@vocal lodge let em know
Yo can I get some help here
Hey! Do you guys know a site that can show what all of the possible angles on the unit circle of a certain function ?
So like if I input sin x = pi/3 or sin^-1(pi/3) it would show me both angles that get outputted
hello guys
where do i go from 48 = r^2 * h/3 (volume of smaller cone)
am i supposed to set some sort of ratio?
Can someone help me idrk how to do this
when the longest side is c and the other two sides are a and b:
acute triangle: a^2 + b^2 < c^2
obtuse triangle: a^2 + b^2 > c^2
right triangle: a^2 + b^2 = c^2
thx
can u help for one more
x = 12, y = 20.8
round to nearest tenth btw
,w 24sin(pi/3)
yes that's right
can someone help w this
if they have equal volume, they must have half the original volume
oh it's asking for height
yeah
is the ratio of radius to altitude the same for each cone?
like would i use that somehow?
yes
since the plane used to cut is parallel to the base, you will have similar triangles
so find the volume of the cone half, then solve for the height
#letemknow
What trig identity do you use for sides opposite and adjacent to an angle?
tangent
SOH CAH TOA
Sorry I should of specified that was directed at Escort
I have indeed passed geometry
126 degrees?
is it actually
I mean the angle of the circular arc is really just the angle between the radii that bound the arc
so the answer is right in front of me...? 😐
As weird as it might seem, that's what it looks like to me
No
then how do i figure that out
There's a theorem that tells you the angle between a tangent and a radius that meet at the same point
let me find it
Tangent Radius Theorem
a line is tangent to a circle if and only if the line is perpendicular to the radius drawn to the point of tangency.
Yes, perpendicular
Ohhhh
my answer was radius = 9 . Diameter = 18 and circumference is 56.54 but I think that’s wrong
,calc 2 * pi * 9
Result:
56.548667764616
oh
Thnxxxx😎
ONE MORE QUESTION
Do you know how I’d get the measure for C
I m really stupid
Calculate the three other angles of the quadrilateral ABCD and subtract them from the total angle sum of a quadrilateral

Help pls
@serene obsidian wrong category, and also wait at least 15 minutes for someone to help you
read #❓how-to-get-help
all good
use a system of two equations
The corresponding sides will be scalar multiples of each other
Ik this is probably a very easy problem but im stuck:
what have you tried so far?
Well ik a straight line is 180 so i tried doing something like: (11 * x + 19) + 44 + y = 180 but im pretty sure im on the wrong track
no, that's totally correct.
now you may want to consider another information you have about the angle y
yeah thats were i got stuck hehe
yeah so, try staring at the diagram and look for pairs of angles that satisfy a well-known theorem
it may help to go over your notes over theorems you may have over pairs of angles.
ok 👍 ill look
is the 2x and 44 degree angle a pair? @upper karma i cant tell if the line is centered or not
a pair of what?
wdym by centered
there are different theorems/characteristics about certain types of pairs of angles
Like are they the same angle in degrees? because i cant tell but i think they are
2x and 44° aren't a pair of congruent angles, keep on searching and trying, you'll eventually come up with the pair that we are looking for.
we are almost there
Ok thanks for all your help i looked over my notes and i think ive got the answer to what y and x =, thankyouuuuuuuuuuuuuuuuuuuuu
Can someone please help
https://cdn.discordapp.com/attachments/326138737606262786/817525717638053908/unknown.png I still need help lol
well the triangles have to be similar to each other since they are dilations so just set some ratios
@cold rune Here's a start:
c^2 = (a^3 + b^3 + c^3)/(a + b + c)
c^2 * ( a + b + c ) = a^3 + b^3 + c^3
c^2 * (a + b) + c^3 = a^3 + b^3 + c^3 -> Simplify
c^2 * ( a + b ) = a^3 + b^3 -> Rewrite cubic binomial
I know that I have to redraw the triangles, But I am bad at drawing them and I end up getting the wrong answers
LMN~LKM~MKN
So this is just in case you don't have it yet. You are absolutely right, the angle of a line is 180°, but it seems you were looking at a line that isn't very useful yet.
Why not instead look at the line with angle
2x+11x+19+44=180?
Then by solving for x, you can then solve for y like you were wanting
Yeah i ended up solving for x and then found y
Okay good. Glad you got it!
thanks 🙂
thank you👍
Hey is anyone on?
Perhaps
i got close cubic spline https://i.stack.imgur.com/JvRpV.png . How best to get interpolation from center ? Just get center pointer?
How many points do you have of data?
If you're assuming it's a circle, Take any one point of data and find its distance from every other point of data. Figure out the expected value of such a calculation for N points of data and work it backwards.
What kind of interpolation are you looking for anyway? You can find the centroid and use the mean distance from it to approximate with a circle.
You can make it a bit closer using the max and the min distance to do an ellipse
Discarding extreme points can help make it more accurate for the most amount of points
AB=AC, (...) then a=?
Where is this a you speak of?
that would be the angle thats shaded yellow pretty sure
yellow
yes
hmm
well
a+b = 180- (16+28+30+14)
@upper karma
i feel like theres something missing
or im just dumb
do you know the length of any of the sides?
nope
I want to learn trigonometry and geometry, which books should i read first
i know basics
You usually learn geometry first. Do you know what sine and cosine are?
no i dont know
What grade are you in and what nation (if I may ask)?
Geometry is usually a high school freshman course. Khan Academy teaches math at a generally relaxed pace. If you think Khan Academy is boring, look into Art of Problem Solving books on geometry.
i knew Khan Academy but i want textbook too
an i am in 9th grade
it can be difficult textbook too i just want to learn geometry and trigonometry very well
I don't have great rec's for textbooks. If I had to give you advice, I'd say go look at geometry books (if you're in the USA) at Amazon.com and check out the ones with at least 30 ratings with high number of stars. Then pick the top few and read the written reviews and see which book matches your wants.
But if you want a tough book ... The Art of Problem Solving series is usually nice.
you should label some of the points to make it easier
what do u mean
and notice that all of the sides are rectangles, meaning they are normal to each other
im quit confused on to where d cuts
label as in writing A,B,C,...
what is?
diagonal d
no, its not going thru any of the rectangles, its INSIDE the rectangle, wait, lemme just write something down
,rotate
yeah ik that but im basically saying like from what point to what point is it touching
i still dont see a triangle
Usually if you want to find a length of a line in spatial geometry, you would want to establish triangles
Yes
So you have to make one
For example, maybe something like triangle EBG?
Since BG is normal to the plane AFGH
EBG is a right triangle
That can be helpful
No
is the 90 degree angle B?
No
Remember, BG is normal to (AFGH)
Hence BG normal to EG
Tho you will need to prove that BG is normal to (AFGH)
im so lost
Do you know what normal means?
nope
Normal is kind of like perpendicular
ooh
Im not really familiar with english, but i think you would usually use normal for a line and a plane
And perpendicular for a line and a line
So basically the angle between BG and the plane (EFGH) is 90 degree
i havent reallt got taught well with planes so i wouldnt know
Hmmm ok
So basically when a line is normal to a plane
That line will be perpendicular to every lines in that plane
So if BG is normal to (EFGH), BG is perpendicular to EF or EG or any lines laying on the plane (EFGH)
im using this as reference
Yes sure
how would EG and BG be perp
like i said above
i never learnt that wooahh
Oh and i forgot
To prove that line A is normal to plane (d), you have to prove that line A is perpendicular to TWO INTERSECTING LINE on plane (d)
So in this example, BG is perp to HG, because ABHG is a rectangle, and BG is also perp to FG, because CBGF is a rectangle
and since HG and FG intersects at G
BG is normal to (EFGH)
ohhhhh
i seee
that makes sense tysm
so to solve for d aka line EB, we first find line EG?
which is 3.6, so EB would equal 6.997?
Yes
Wait, lemme check the numbers
But the method is right
For EG you should just keep it as sqrt(13)
And round your number when you found EB
(If needed)
@unborn bison $\triangle KLM \sim \triangle GML$ and why are the points renamed there?
Roenbaeck
@unborn bison I'd set up some equations, given that the triangles are similar, so their sides are proportional. If that still leaves you with some unknown, use Pythagoras as well, and you'd surely have an equation system that can be solved.
@unborn bison If you are allowed to use the geometric mean theorem, you could use that, yes.
I have to find AC how do I do that?
thats AAS postulate
subtract 118 and 22 from 180 to figure out the angle c
and then use the law of sines to work it out
heres an example of how to do it
Hi there. I am trying to find the area of my living room. However I don't know math well. I just measured the length and the width, but it is a trapezoid. so if I multiply the width with length, I get more space than what it is. Can someone help?
It says here if I take the length of the long side, as well as the length of the short side, then add those, then take the depth as well, and times that with depth, then divide by 2. I will get the correct answer.
Yeah, that seemed like it worked.
huh, its 350 square feet. nice. Now I know.
for future reference, try dividing an odd shape into shapes whose areas can be measure with simple geometry, like how a rectangles area can be measure with base * height and how a triangles area can be measured with half of that
@quaint plinth
Can someone explain rq what law of cosines is
Hi! Um,,,,can someone help me out with this?
For this, you just need to use trigonometry
SohCahToa
@severe latch You mean 7?
Oh, I was not looking at the most recent messages.
Introduce the green line as in this sketch, that should help you.
@WOWWA#3261 ^
i need to find x
are there any angles
hm
someone told me that i can solve this with similar triangles thing
you might have to create a few polynomials and once found the variable do multiplication ex 4x
yeah try the similar triangles first
I tried but i failed
Why are inverse trig functions constricted to only two quadrants?
How are we supposed to know about the quadrants?
I need help with geometry homework. I don’t know how I am supposed to label which side is opposite,Adjacent,and hypotenuse
I think I have it. When I tried that I got the answer as cos
nice
thank you👍
np 😄
Shouldn't the triangles be similar, not congruent?
Okay so if I am not mistaken, the ratios of the sides should be the same.
So $\frac{6+2}{6}=\frac{5+x}{5}$
That should get you both your x and y values
dackid
for the below triangles the angles are 30 90 60
responding but i also have question
what
so ur trying to find the cosine of angle a?
well i mean
a cosine is a trig function
and since cos a is unsolved im guessing u wanna solve for cosine
cool
Read my answer directly above this picture. It is the exact same type of problem.
apply law of cosines like it says
pythagorean theorem
ohh
I did I got 36.9396 and it still says wrong
write out the calculation?
ohhhh
$c^2=a^2+b^2-2ab\cos{C}$
moshill1
cosine law
Can anyone help with #2
Should be simple for some of you but I'm a little stuck on a
Worked the rest out no bother but I can't find a rule that suits a
I do not encourage you to simply solve the problem for them. That does not help them understand it.
I need help with these proofs if anyone can help. :)
I am unsure how to use the Reflexive Property or where to go from ST = TU
If anyone responds please ping me, I have tons of discord servers, thank you.
@hardy pasture so in order to show two triangles are congruent, one way is to show all the sides are the same
We've looked at two sides for each triangle, but there is one more side we need to look at.
what is this website
Ayyy, you got it!
Would it be the same case here?
You sent the exact same picture so yes. 😆
If it were different, why do you think it would be?
I mean the angles and sides are different, but I was referring to the concepts.
Does anything about this suggest the approach to solving it should be different?
No, I do not believe so.
And your intuition is correct.
Thank you, one last question.
I tend to doubt myself even if I believe something is correct. Will you look over this, and let me know if you think its correct?
It's pretty clear you don't need my help 😉
Have a little more confidence mate.
You're doing just fine
Okay last last one.
What property would I use to state that two triangles share a set of angles or sides?
Wouldn't it be, SAS?
Is this after you prove congruence?
Also couldnt the final answer also be CPCTC?
Yes.
What is CPCTC?
Corresponding Parts of Congruent Triangles are Congruent.
Ah okay. That is my thought on your most recent question
Wait what?
I know SAS and SSS, and I also believe ASA is one.
However, both AAS and ASS are not ways you can show congruence.
Perfect thank you!
So first thing is first, what is the measure of a right angle?
- its a right angle so work from there
- whats the sum of angles on a straight line? and work from there
Okay, since the sum of the angles 75° and x are a right angle, how can we find x?
See if this helps
Think about what you just said and ask yourself if that claim makes any sense.
p. s. I will absolutely help you, but I will not give you the answer
Why does what you said make sense to you?
You are in the wrong server for that
There are also rules that must be followed.
And this
This server is exactly what it's designed for. To band people that are doing math together and help out the people that are struggling.
Regardless of the language, I am still willing to help. But once again, I have no intention of giving away the answer
You can do what you will with that
180-75= the missing degrees. If it is a 180 degree angle and they give you an angle then you need to subtract to achieve the answer.
This is an example not the answer. I hope that helps you find the value of x.
Yes, x=15 in your problem
So go back to your picture or the picture given and figure out what values you need to use
To find the value of x
I think they just did shiro
Indeed I do
Okay so I have a question if you don’t mind. I can break down the unit circle but when it comes down to like 5pi/12 I have issues with identifying what the angle is.
Do you know an easier way to identify the (x,y) or the angle.
Isn't 5π/12 the angle?
Do I need to multiply 2/2 by pi/6 to obtain it
So when I make the physical drawings of the unit circle I just get so confused
Yes
Yes, but it can be particularly difficult to find
Gotcha thank you
There is a nice way to do it. But if you haven't learned yet, then don't worry about it
I’m currently in college trig but I think I’m getting lost and behind. So I may have lots of questions. :/
So you haven't taken calculus yet?
Not yet
Dang! Euler's formula makes some trig identities so easy to produce
Don't be afraid to ask :)
Thank you! 🙂
ye
jan Niku
Why are u guys mentioning specific people
its a secret
@upper karma if 180 - 77 = 103 and 103 > 90 then ur all good
What are u trying to find
Well how many degrees is a circle
Not edge degrees
How many
Ok
So u have 250 of those degrees
And abc makes up the rest of the circle
Do u have the answer?
Huh
Well that just happened
did you also get a random ping
Well I told the person to stop mentioning specific people
Then they told me to stfu and purged their messages
what
i can still see them though
oh weird
Yeah
your right
yea and it was not that bad of a question
Cuz they kept mentioning other people
Uh
wonder where they went
U know that you are the one who did it right @upper karma
wth
That's what I'm thinking rn lol
I think that they are trolling or hacked
@fast pulsar is this correct?
Wait ur trying to solve sin x / cos x - 1?
Cuz there's a lot to do with identities here
Trig is so fun
Hmm
Well using a conjugate is a good idea
Hmm
How did u get sin²x on the bottom
Hmm
Sin^2theta + cos^2theta = 1
I was told to do each section at a time so if cos^2 -1 if I were to set to zero I would get sin^2x+cos^2x=1
Hmm
But it isn't set to 0
So then at cos^2x-1 can it be canceled by the numerator
Before distributive property is done
To sinx(cosx+1)
hiidostuff
Which is unfortunately right where we started
Honestly I don't see why this would need to be simplified
Why are u simplifying it?
It is apart of the hw question
What's the whole thing? Because this seems already fairly simplified
Yes
And I got this
Yeah thats correct
Yup it said to simplify
Honestly
I have no idea
Because to simplify that u would get what the original thing is
Because $\frac{\cos x + 1} {\cos x + 1} = 1$ so uhh
hiidostuff
Are u sure it doesn't say cos x - 1 / cos x + 1
So I got a different answer and now it’s not simplified enough
So the answer was 1-cosx/sinx
X=theta
which part?
I figured mine out ignore it.
Glad you were able to figure it out
Care to share what you've tried/ the problem for what you have tried
Hey how would I solve an equation like this x√2=9
what makes u think thats geometry
ive been trying this for like 20 minutes and havent got anywhere
can soemone pls help
nope
yikes
so ur right about the side length that u actually have
but
its only one side length
yeaa so idk what to do from here
i guess u could say $\tan{R} = \frac{f}{e}$ and $\tan{\gamma} = \frac{f}{d}
hiidostuff
Compile Error! Click the
reaction for more information.
(You may edit your message to recompile.)
so $e\tan{R} = d\tan{\gamma}$
hiidostuff
and u know e and d so $1.5\tan{R} = 9.5\tan{\gamma}$
hiidostuff
and this is where it gets difficult...
i guess $\frac{1.5}{9.5} = \frac{\tan{\gamma}}{\tan{R}}$
hiidostuff
🥲
yeah this is pretty painful
but perhaps we can end up getting a single function
perhaps
f
alright so tan = sin/cos
so we have to look back at what tan gamma and tan R is
oooh
i think we can solve for f
hopefully
so we have $\frac{\tan{\gamma}}{\tan{R}} = \frac{f}{d} / \frac{f}{e}$
hiidostuff
crap
the fs cancel out
f
hmm
its like midnight where i am i dont wanna be tired and screw up ur math so id mention helpers
sorry
ookayy thanks for the help tho
i understood a little bit hehe
<@&286206848099549185>