#geometry-and-trigonometry
1 messages · Page 348 of 1
if you were to consider HK as your base,
the altitude to that would be MJ
you could also use Apollonius theorem + pythag
its asking me for the scale factor to get from the base of the large pyramid to the base of the smaller pyramid at the top, but im not sure how to do it (??)
The triangles in the top pyramid and the whole pyramid are similar.
You can set up a proportion between similar parts.
so like this?
144 = height of the whole/biggest pyramid
144-96 = 48
48/144 = 1/3
1/3 is the scale factor (?)
(dilated from the apex)
Can someone tell me why I'm getting these wrong?
i managed to get it done thx!
would anyone pelase help me
whats up
can you please show me how to solve the one aboce
What's a recommended software to use to do geometry? For example, for working with parametric curves?
Is MATLAB the best option?
Try using the proprieties:
• cos(2x) = cos²(x) - sin²(x)
• sin(2x) = 2sin(x)cos(x)
And expand the right hand side using tan(x) = sin(x) / cos(x)
xi64
@onyx marlin
there is a typo btw
(a - b)^2 = a^2 - 2ab + b^2
i mistyped + instead of -
$4/3 n + 3/4 = 1/2$
rayy
what is the question ?
Hello i really can't find any material on my issue because i don't know what this is called. Basically, the exercise goes like this:
AB=5cm
I need to find points (named T1,T2,T3...) that are 2cm away from AB.
Also the angle ATB must be 90°
Help please, i don't even know what method to use to get these points
I don’t really know what you are describing. It sounds like ATB is a triangle with hypotenuse AB = 2, but I am not sure what you mean by points away from AB…
Do you have a picture?
consider circumferences
@inland salmon calculate the circumferences of each circle
that is the equivalent of 1 revolution
@delicate lagoon these triangles must be similar, so just select all the ones that show the correct proportions
HELP
I think it is
There are multiple ways to inscribe octahedron inside tetrahedron right?
🙏 pls
I think it is, but I'd rather get confidence from you before approaching my teacher
The altitude is perpendicular to the bottom line, which is why it forms a 90-degree angle. Using supplementary angles, and the total degrees in a triangle, you can solve the left triangle. Then, you should be able to solve the rest of easily.
dont know how to do this
125˚ can't be obtained by summing and subtracting
so
you might have to use a calculator
unless someone else knows
¯_(ツ)_/¯
ok thx :)
B is calculated finding the hypotenuse of triangle ACG.
you can use pythag to find AC then use pythag to find AG
@upper karma angles in a triangle add to 180 degrees and the little squares in the triangles represent 90 degree angles
thats all im going to say
find AC first
7.2^2 + 9.6^2 = x^2
x^2 = 144
x=12
then same thing for AG
C is finding the angle of GAC
the angle line AG makes with plane ABCD
you can use trig to solve for GAC
np
So tan 3.5/12?
yeah you can do that
but
you have to use the arctan function or tan^-1
because your solving for an angle
It should be considering the volume relation between pyramids and prisms is 1/3. I don’t think it matters that it is a right pentagonal prism, but if someone could confirm, that would be great.
Let's say I am given a "box" (not drawn to scale) with the following side lengths. Would there be a way to figure out the metric given this information?
x_1 and x_2 are colinear, and so is y_1 and y_2.
Is the box supposed to have all sides equal?
Or just opposite sides or sth like that?
Not necessarily, just opposite sides. In this particular case If we choose x_1 = y_1 = 0 it will collapse to a right angled triangle, with the hypotenuse corresponding to that you would get using Pythagoras. So it's very likely that the metric is the usual metric on R^2.
I would not like to employ that trick though, and I'd rather figure out how to get a metric out of that. Even if it means more conditions have to be satisfied. I'm working on a paper and I will be getting more exotic boxes than that one.
Aaah
This also might be a better fit for #point-set-topology tbh
This isn't exactly at the pre-uni level haha
Ah, true 🙂 I'll give it a try there, thanks.
No worries. I'll be trying it too, although I don't know of any metric besides L1, L2 and L∞ 😛
And the discrete metric obviously
@tiny snow I guess the fact that $\sqrt{x_1^2+y_1^2}=\sqrt{x_2^2+y_2^2}$ is independent of our choice of metric since these are just real numbers, right? This gives us $$(x_1-x_2)(x_1+x_2)=(y_2-y_1)(y_2+y_1)$$as a constraint. Would this only be consistent with the $l_2$ metric?
Manan.
Since we want $d(y_2,y_1)=d(x_2,x_1)$
Manan.
No, that box actually looks like this (roughly sketched)
Aahhhhhh
So uh, you want to find a metric which ensures it retains a convex quadrilateral shape?
(given that the dimensions are as mentioned in your last diagram)
My goal is to figure out that given those side lengths I must be in the real plane, and not, for example a hyperbolic plane.
Hmmmmmm
Okay, so we're confined to R^2 and metrics on R^2, which ensures the above figure stays a convex quadrilateral
Let's just work with the assumption that none of the four values is 0 to avoid collapsing-into-triangle kind of degeneracy
Also, x_1 and all that don't have any relation to coordinates, right? They're just real values?
They're just real values.
Okay
I think there's some constraint missing in order to get a handle on this.
Honestly I think so too
I'd be amazed if this problem could be solved with only this much information
I'm still trying to wrap my head around the problem itself lmao
I also think the values of x_1, etc. would impact the choice of metric
I can choose x_1 and x_2 freely as long as they are colinear, and same for y_1 and y_2.
So, making those two sides equal in length is possible.
What would it mean for x_1 and x_2 to be collinear? They're just real values, right?
I mean, geometrically they're along the same straight line on the space.
Is that a constraint on the coordinates of the box?
Any two points on the plane are collinear anyway
You can always get a line through them
Yes, sorry, these are on straight lines. I don't want to rule out that there could be other lines through two arbitrary points. Think great circles on a sphere for example.
Hmmmmmm
Maybe I should rephrase the question to how much information can you get about a space, if you can construct boxes with various side lengths at various places in the space 🙂
Sure, that might help!
I'll try thinking more about this problem, limited as my understanding of both geometry and analysis may be. 😛
Thanks for the help so far!
I wasn't able to add anything meaningful. Let me know if you have any updates!
Truth or deception?
I mean given that's not pi, deception
However the problem of squaring the circle under using a straight edge and compass is known to be impossible
ohh yeah that's what i meant tyvm again
I solved that problem too.
Ok.. how?
cause given you posted something with an incorrect value of pi, I doubt you did
Did you check the squaring of the circle with that value 3.1630625 on calculator?
why would I use that value?
It's not pi, so using that value isnt the area of a circle w/ radius 1
wait, I will send you.
I asked for your proof of squaring the circle under the typical restirctions
not a radian calc
I'm sending you a PDF
cool, can you stop fucking pinging me
ok, sorry
You did not solve a problem from ancient Greece if you used a value of pi that isnt pi
I'm talking to you, so it's my habit. Sorry again for that...
Why are you immediately convicting and you haven't even looked at the evidence yet?
cause what you have posted is grounds enough to null your proof
so yeah, 2nd line already missed the point of squaring the circle
which is that you cannot create a square using a straightedge and compass that has the same area as a circle
Squaring the circle does not say it's impossible to make a square with the same area period
Do you have a better solution?
cause that's trivially define the side length as $\sqrt{\pi}$ and pack up
moshill1
No, since it's known impossible
lol
no amount of precision in your straightedge, even if it's graduated, will give you square root of pi
since sqrt(pi) is irrational, and thus always more decimals
🙂 Ok 🙂
I don't want to argue or convince who is right. I just want to share what is reasonable and logical. He who has eyes, let him see, and he who has ears, let him hear. With love.
Then share something reasonable and logical 
I've already done that.
You did not, since the 2nd point of that article asserts that pi is rational, yet it is not proven that it's rational
whereas pi has been proven to be irrational, transcendental at that
@torpid hearth Pi is a rational. Check countless times in countless ways.
I did make one big typo/mistake in the video: at 3:40 I claimed that f(x) is a polynomial with integer coefficients. I meant to write n!f(x) is a polynomial with integer coefficients. Commenter ffggddss also pointed out some other typos/smaller mistakes in the video which I have pinned to the top.
As it's impossible to simply edit the video on ...
There is a lot of garbage on Wikipedia and on the Internet. The truth is barely noticeable.
I can't tell if this is a troll or not
It's clearly a troll
Now prove it's transcendental 
moshill1
this is so sad
who takes the time to make a fake research paper
If I’m a troll, I’m sorry I came to this channel of my own free will. 😦 It is easiest to condemn. I was born in the country where Nikola Tesla was born. As a token of love, I will greet you.
and they gone
Lol
need help
With what specifically
the whole thing 😭
That's a lot of work
I mean I can just generally teach you how to do proportional triangles
sure please
i keep getting decimals in my answers when im solving x
and idk if thats right
for number 2 i got 12.6 for GH and 9.6 for Kj @wintry tundra
If its only tenths then probably right
As long as ur taking ratios for lengths of similar sides
Which ima guess u are
Also don't expect to get all the answers bc here we only help you get to the answers
So its mainly u that gets the answers in the end
can someone explain this to me? my english is really bad and im not very good at word problems
ohh i see it now, thank you!
It’s a square pyramid
You have the diagonal of the square from (c), and you’re solving for the side of the square
Do you know special right triangles?
actually wait you don’t even need that
do you know pythagorean theorem
Anyone know how to do this?
Do you know the double angle identity for cosine?
Yep
what do i do with it
Which one can you do with the info you have
the second one
plug in where
You can use $\cos(2A)=2\cos^2(A)-1$
CST
Since you have $\cos(A)=\frac{\sqrt{3}}{6}$
CST
how i get cos^2 in my calculator
you don’t need the calculator (cos)^2
ok
Omg I'm literally not thinking damn I feel dumb but thank you I get it now
what do i do
im confused
square the value you have, then multiply it by 2, then subtract 1
thanks, got it
oh wait nvm this isnt the help channel
This is the help channel
@inland dagger What have you tried so far?
@inland dagger Do you still need help with that question?
49
@inland dagger
find scale factor:
ST and SQ are corresponding, so we can divide those to find the scale factor
42/24 = 1.75
TQ is corresponding to QR and we know what TQ is which is 28
28 x 1.75 = 49
so, QR = 49
Hey guys, this may sound as a stupid question, but how can sine/cos have inputs > 180 degrees. from what I now those functions are just the ratio of triangle sides. triangle interior angles add up to 180. so there is no triangle with angle > 180. what am I missing? 😢
Those functions are based on the unit circle, but can be applied to triangles.
so later on I will learn the relation of sine/cos etc. in relation to the unit circle?
I am already solving unit circle problems now without a problem, It's just that I don't really grasp the full picture/relations
Yeah. Essentially, anything greater than 2π radians (360 degrees), the angle in those trig functions yields the same value as that angle minus 360 degrees.
So you wouldn’t really have a 400 degree angle in your triangle, but you could have a 40 degree angle since it is the same value within the trig function.
hiidostuff
Also lol 69 nice
So it’s pi over 5? @wintry tundra
Mhm
Thanks
Np
tan is odd, so $-\tan{x}=\tan(-x)$
moshill1
@humble pulsar so ya what’s the answer
2 square root 5?
why is it that?
by doing what?
Idek
Ok then idek if it's right
Why so mean
It's not mean, trying to see if you actually solved it or blindly guessed
Besides, the final answer isnt important 99% of the time
I guessed idk how to do it
what's the relationship between cot and tan?
I forgot
Ok so look at your notes, or the trig cheatsheet that's pinned in the channel
Not doing all that, just gonna guess
Ok
Yoiu have a 25% chance of being right
😑
Look, if you wanted to learn how to get the answer, I was more than willing to explain the couple steps it took
I gave you a nudge with how to get tan(-x), then told you you need a relationship b/w tan and cot, also told you the relationship was pinned in the cheatsheet. I did help you, and did try to explain it
I am not going to spoon-feed someone answers if that is what you expect help and explanation(s) to be
Damn u one of those smh
Yes, I'm one of those people that actual helps
@humble pulsar well thanks anyway
Ahh ur one of those smh, those who want the answers spoon fed to them
no im not
Thanks bro! 😃 Appreciate the info!
Well idk why u boxed only sin(x) = A
When the equation is actually arcsin(x) = A
Where arcsin is the inverse function of sin
yea that was a stupid mistake
not sure how to find the arccos and if it can be a real value
Hmm
Well sadly the arc mistake is really the only thing I can help with
Sorry
But maybe someone else could help out
it is ok just not sure where even to begin tbh
sad
yea
intesesting name tho
ahhaa thanks
sorry i can't
that's hard for me
yea math has never been my thing
i was the smartest in my class until 3rd grade lol
damn
ii think my besties influence me
hahah how old are u
me too i will be 11th grade next year
nice
i just turned 17 yesterday lol

what is it that was confusing about circles to you? i could help you with that
lol the whole thing but lukuly i passed that unit
i really appreciate the help tho brodie
np
i mean i guess one thing to remember with circles tho is that most things you are trying to find in geometry with circles relate to how much of the angle is to 360
Amazing pfp hiido
thank you stephen
whoa picture is amazing lol
usually i struggled with the tangents cosign and the other one
i would struggle to identify each side
but if you have an angle whos joining point is on the middle of the circle, the curve at the end, like the crust of the pizza slice, it will be the radius times the angle
and how to solve
tangent cosine and sine?
ahh i see
just remember that they are ratios on a triangle
like comparing sides
the reason we even bothered to have sine cosine and tangent is because you need to find weird ratios of triangles all the time
if ur in engineering or physics that is
but for my robotics team i am mainly the mathematician and i have to work with circles a lot for wheels
and holes being cut in parts of the bot
which are usually circular holes
but good luck with geometry and algebra 2 next year is what i guess u would take
Here, I have this drawing for you at least
Stop double pinging, please.
OK
Did you get this question answered?
oops
@slow fossil
alright I solved it


Imma go to sleep so i'll just post the answers
sorry it's a bit messy lmao
hi, can someone help me figure this out? i've been trying to solve it but i'm so confused
if i trying to do tan (x) = sin(x) / cos(z) its cant be? The one and only case is tan(x) = sin(x)/cos(x) ? 🙂
it has to be the same angle or value
That doesn’t factor nicely. Can you use quadratic formula for what you are doing?
Well it actually does if you use a different method other than the quadratic formula
what is the ratio of cosine? (Hint: SOH, CAH, TOA)
@vague helm
Um I’m very new to this and don’t really now how to do it at all
here are the 3 trig ratios
So what way would I answer the problem in?
keto11
a ratio is division between two numbers so...
keto11
Ok so how would I start putting the numbers in?
the first thing you want to do is actually draw the triangle, it's a lot easier to see what's going on
@vague helm are you able to upload images to the discord?
kk ping me when your back
@torpid hearth ok I’m back
okay good
now you have to identify which lengths are the hypotenuse, adjacent, and opposite
@vague helm
what's the definition of a hypotenuse?
Oh shit so ON
which angle are we looking at?
Wait what?
We're trying to find the cosine of angle N
Oh ok so what will the equation look like?
well you have to identify the sides...
you already have 1, the hypotenuse is NO
do you know how to identify the sides?
So cos(90) 77/85?
90 is the right angle not angle N
So would I replace 90 with X?
cos(N) = ?
So cos(N) = 36/85?
from back up here
So I can use a calculator to answer the question so how would I put this into a calculator?
stop rushing for the calculator
you already have the answer
What is the question asking you to solve for?
yep
the only reason you would need a calculator was if they asked you to find the value of N
then you would have to do the inverse cosine
Yeah and I’m gonna need that soon
I’m gonna finish this one. Then next thing that I don’t know I’ll ask I guess
kk
now you wanna draw the angle that you're solving for just like I did here
What's the ratio for sin of an angle?
it's these ratios
So it’s 20/29?
Oh so 21=20/29?
what's 21?
in addition, be aware of what you are saying.. 21=20/29 is blatantly untrue, this is the same nonsense as saying 0=1.
P=20/29
keto11
Oh so sin(P)=20/29
how do you isolate P?
Um idk
if in the last problem to find the value of angle N, you had to take inverse cosine, then to find the value of P you need to take...?
keto11
So what will be A and what will be B?
keto11
here
Oh so the answer will be 0.69?
Result:
0.68965517241379
o frick me
what pattern do you see here?
For like the template of the problem?
Oh so cos wouldn’t have the negative?or that’s it’s not inverse?
what is the inverse cosine?
Cos-1
and what have I highlighted here?
Cos-1
so to cancel out cosine you use inverse cosine, then to cancel out sine you use ?
Inverse sine?
yeah
keto11
Ok ok understood
keto11
So now I have this problem because I finished the section that had the questions you helped me with
Also understood
So how would I go about answering this?
Identify which sides are opposite, hypotenuse and adjacent to the angle G
So Hypotenuse is I, Opposite is G, and Adjacent is H
those are angles, sides are line segments
All of these problems are basically the same, why don't you try to work it out on your own for a bit. Use the stuff that I posted above if you get stuck first
Oh ok
@vague helm did you figure it out?
,calc 8.9 tan 48
The following error occured while calculating:
Error: Unexpected type of argument in function multiplyScalar (expected: number or Unit or string or boolean or BigNumber or Complex or Fraction, actual: function, index: 1)
@torpid hearth no, no I don’t
I’ve been trying for an hour now and can’t even get past the first question
wassap?
it's because you're using desmos
later on in math you'll learn about something called radians it's a unit system for degrees basically
if you want to fix it for desmos you want to do this
So what do I do with my desmos?
Yeah I see it and I clicked
radians should be highlited in black, click on degrees and you should get the correct answer
keto11
@vague helm did you figure it out?
which one?
the last 4 pgaes
when you have similar triangle, you have a special unique attribute, can you guess what that is?
they have a relation of similarity
@zealous forge are you here?
yeah
all right, so when you have a pair of similar triangles, you have a ratio between them
to calculate that ratio, you divide two proportional sides from each triangle
ok
if BE = 9
AM = 3
ET = 12
then the ratio must be 1/4
since AM and ET are proportional
AM comes from the triangle RAM
ET comes from the triangle BET
and for that reason, what can be inferred?
what can you conclude from the ratio of 1/4
if the smaller triangle is RAM and the larger one is BET
and they have a ratio of 1/4
what can you figure out
BE
BE is already given to us, it's 9 cm
but what can you see and say about the relation between the two triangles?
one is smaller than the other
but by what?
is that its 1/4 smaller
yup
ok thank you
anything else?
ok can you help me with the last 4 questions please? i think i can figure out everything else
sorry for asking alot
it's fine, I'm here to help ya
?
i think we have to find the area
so what do we need
perhaps some trig could do the trick 🤔
nope
bullseye
Nice thats cool
but now
what kind of trig could we use to do this?
(hint: this is not a right triangle)
yeah sure
sorry wdym by trig
trigonometry
ok 1 sec
yeah]
yup
so its should be side a
wait no
plus side b
mate
right
Ok
so
the missing angles is
93
and now i can use the formula because i ahve 3 angles
ok
ok
thank u so much
1 sec
am gonna solve and may u tell me if i got it right
please
ok i got for the first side which is A its equal to 7.4
i used the know one to find the of the other sides
uhh, what?
i ddi this
all right, now find x
ok i got 5.845
and a bunch of ther numbers
its not fo a though
nbm
nvm
1 sec
A=7.4
okay
B=5.8
weird
Wait 93 degree angle?
yeah
What shape
Oh ok
np
Did u solve it already?
Ok
Hmm
9.7 / sin 37 = a / sin 50
Will give u one side
Then u can use law of cosines to find the last side
And there u go
Problem solved
So @zealous forge now u should be able to solve ur issue, if you know law of cosines
Goddamn
didn't I tell you to use the law of cosines? @zealous forge
Do u know law of cosines?
no
yeah but idk whats that
$c^2 = a^2 + b^2 - 2ab\cos{(\gamma)}$
visual of Petter's ascendance
I don't recall myself telling you that
telling me what
to use the law of cosines
If you use the law of sines, you can find both sides u need to find x
Gamma is the supplement to the sum of the other angles
So boom
That's what u need
so if i find the fist side i use that and the orgiginal lside to find X
Yep
ok thanks
idk what that law is thi
Remember x has to be larger than 9.7
tho*
I told u that law
This is that law
The cosine is why it's called law of cosines
ok so anything larger than that i can be sure that its right
oh i didnt know that
Yep
Bc think about it
If there's a large angle then it's opposite side also has to be big
Bc the angle makes a lot of space to connect
And 93 is bigger than 50
Yeah

lets goooo
ok i need one more
so in this law
the variables are the angles not the sides right?
Ok remember this
English letters are probably sides and Greek letters are probably angles
This follows the same thing
a and b are your known sides
And the weird curly thing called gamma is the angle opposite of c
c being the side ur trying to find
so what do i plug in for c^2,a^2 and b^2
a and b are the sides you know
i still dont have 3 sides
c is the side you don't know
Yeah ur trying to find c
The right hand side is solvable itself since a b and gamma are now defined
Doesn't matter what sides you put in for a and b
Gamma angle does tho
Has to be able opposite of c
So $c^2 = 12.3^2 + 9.7^2 - 2(12.3)(9.7)\cos{(\gamma)}$
visual of Petter's ascendance
Is what u should have
ok i understand now
how do i make photos like u
when i write an equatin
equation*
yeah no thanks am just gonna draw it and send it here
There's so many math functions and therefore so many things to do with the math thing called texit
what is it?
$2ab$ is not equal to $2(ab)$
visual of Petter's ascendance
For 2ab you only double one of the variable values
For 2(ab) you double both
Here you have 2ab so only one
Would 2(ab) be 2a + 2b?
missing side
wait x in the question?
Only multiply 12.3 yes
ok
2(ab) is 2a2b
So no addition?
No
visual of Petter's ascendance
Gamma is 93 degrees or 93pi/180 radians whichever one u like best
Degrees is better here so use degrees
so what shall i do from here
Multiply the end part by cos 93
so -24.6(9.7) cos 93
Is ur calculator is radians mode?
nah am using google as my calulator bro
Hmm
End result should be 12.5
ok 1 second
Your calculator is set to radians
Set it to degrees
Or change 93 to $\frac{93\pi}{180}$
visual of Petter's ascendance
yeah
ok iwill
omg
its right
12/5
12.5
Yep
Thank you so so so much dude
damn ofc u gotta ruin the moment
Now you have $c^2 = 12.3^2 + 9.7^2 - 12.5$
visual of Petter's ascendance
so i just solve then what ever i get is c^2 right
which is x
Yeah
right then am done
Mhm
what now lol
Alright
So c^2 is equal to that
So what should we do to 233 to make it equal to c
Wait
Is that an answer on your homework
Bc that isn't riggt
Did u solve this? $12.3^2 + 9.7^2 - 12.5$
visual of Petter's ascendance
Or evaluate it I should say
Oh
thats whyy
its all good
i hope its right this time
16.0586425329
so 16.10
uhh fianlly
thank you very mcuh Sir
Yep
for helping me with this
Np
Could i ever ask you for help if i need some in the future
Heck yeah I help pretty often
I'd ask for helper role but I don't wanna get mentioned all the time
So dms would be fine by me
alr so your like an undercover helper
Not really undercover
Ima be honest I haven't taken trig yet in school
I just self studied it
A while ago
And I'm not bad at it since I use it in my robotics club and engineering somewhat often
are the semi circles at at right angle
yes
I think then they should both intersect at the apex
I honestly have no idea I dont see any given angles or line measurements
pretend the radius is 1
what specificaly are you trying to find
the exact cordinate of the intersection or just information about the semi circles
the area of the part where they intersect
oh ok
I have no idea how to help you out with that I would post that in a questions most of them seem to be open
thank you
anyone able to help solve sin^2(x/2)cos^2(x/2)=(sin^2x)/4
uh
double angle identity
thanks feel stupid now
If a point is defined as being dimensionless or according to Euclid 'that which has no part', then how can it represent anything geometrically. I think this confusion is arising because we use a dot to represent a point but the dot obviously has a part to it which can be observed on zooming in. Can anyone please help me?
do you have a calculator with buttons for inverse trig functions?
