#geometry-and-trigonometry
1 messages · Page 117 of 1
I can help with anything at a pre-uni level
So yea on SAT I would have to know the identity
I know this is math server but can anyone recommend to one of Physics and Chemistry
sin(90-x)=cos
cos(90-x)=sin
thank you
Why are you challenging people?
x2⋅t=x2+x
x^3=x^2+x
show that 0 is a solution, then in the case x is not 0, devide both sides bys sqrt{x} to get quadratic
a≠0
this is very rude.
whats very rude
Pretending he can order helpers around to race for completing his tasks.
acosA-bsinA = c. Prove that asinA+bcosA = + or - sqrt(a^2 + b^2 - c^2)
how do i even. I dont even know where to begin. Doing from my older siblings book and its written that its similar to the question
"if sin^2(A) + sinA = 1. Prove that cos^4(A) + cos^2(A) = 1."
My mind is still blank
do i square? or somethign
take a look at what problem asks, it has sqrt and square in side the sqrt so I would say yes
alr lemme like
Square both sides then take sqrt seems like a good way
i see a bunch of sinA and cosA
i have a feeling pythagorean identity is goanna be used.
but like
how
the hell
do i
what if i just like
isolate a, b and c. And then take their squares and then like.
yeah, use it twice and you'll get the answer
how tho
oh also random but not random question
can i like
write -xsinA as -x*(-sinA)
no wait
thats a stupid question now that i think of it
😭
What did you get after squaring both sides
a^2(cos^2(A))+b^2(sin^2(A)) -2absinAcosA
= c^2
the variables are different
cant factor a and b
using pythagorean, cos^2A = 1 - sin^2A
a^2 -a^2(sin^2(A))+b^2(sin^2(A))-2absinAcosA
Do the same for b^2(sin^2(A))
1- cos^2A = sin^2A
no, coefficient of cos A is now b
and for sinA is now a
ye
Exactly what we want here
asinA+bcosA = + or - sqrt(a^2 + b^2 - c^2)
what if i
a^2 - a^2(sin^2(A)) + b^2 - b^2(cos^2(A)) - 2absinAcosA
what if i like. a^2 + b^2 - a^2(sin^2(A)) - b^2(cos^2(A)) - 2absinAcosA
then i
-( a^2(sin^2(A)) + b^2(cos^2(A)) + 2absinAcosA)
which is uh
(asinA+bcosA)^2
oh wait wait
OH YES
a^2 + b^2 - (asinA+bcosA)^2 = c^2
-> - (asinA+bcosA)^2 = c^2 - a^2 - b^2
yikes
that took some brainpower. Now i must sleep.
you can also use middle term splitting and i must say that its far much easier.
wait no?
yeah it cannot be factored using middle term splitting.
mb
trig
(and geometry)
just passed my trig final with a beautiful 97 🙏 now to move onto calc
Woooo
I notice Law of Sin looks like pythagorean theorem
Really
a^2= something
b^2= something
c^2=something
?
Oh okay makes sense now.
Does it look like pythagorean theorem?
theresactually a fun reason behind that. when the angle is a right angle, then cos(theta) = 0
It is an extended version of Pythagorean theorem.
it is the pythagorean theorem (but big)
Also using (a+b)^2 I assume
Pythagorean theorem only works when $\theta = 90\degrees$.
Restarter
Compile Error! Click the
reaction for more information.
(You may edit your message to recompile.)
And also how come Law on Sin is a proportion
Law of Sines is basically comparing the sides of the triangle with its altitude.
Is this 88?
Or 53
Its not exterior angle thereom since that needs the shape to be defined as a triangle
,w find 180-(5x+10)-(12x+32) if 5x+10=3x+20
this
Why is exterior angle theorem used if its not defined as a triangle
you could use the exterior angle theorem, but you don't have to
I just did alternate interior angle spam
Oh
god damn i was breaking my neck in order to see the picture and just forgot to scroll down a bit 😭

i dont have nitro so i just made a photo
If im given 2 angles in a quadilateral, can i find x using only the 2 angles
But i know its a parallelogram
Please show the original problem, exactly as it was stated to you, with the entire original context. A picture or screenshot is best. If the original problem is not in English, then post it anyway! The additional context might still be helpful. Do your best to provide a translation.
how are they both parallel?
shouldnt it be NA||LO?
or is ANOL a ||gm?
Thats whats given
ok so that means that 4x^2 - 13x + 122 + x + 58 = 180. (co-interior angles)
bring that 180 to LHS
From theres its just quadratic formula right?
no you can do it by factoring too
what do you get after simplifiying 4x^2 - 13x + 122 + x + 58 - 180?
4x^2-12x+180-180
which is
4x^2-12x=0
x^2-3x=0
3x=0
Ohh 4x(x-3)
oh you have to solve for it?
I don’t know, it leaves it vague
“Given the image below of a quadrilateral nola, with NA II AL, m<NAL
so find angle NAL?
I think
ok so for that lets continue from 4x(x-3)
here. We know that 4x(x-3) = 0. Which must mean that either 4x = 0 or x-3 = 0
because the answer of a product is zero if and only if one of their term* is zero.
variable?
idk i forgot the name.
i think its like a uhh. TERM
fuck
X-3
0+3
X=3
It would just be undefined
X=0
yeah so x = 0 or 3
now plug in x = 0 into 4x^2 - 13x + 122
and then do the same but plug in x = 3
its prob 3
This questions was so stupid since we weren’t taught anything about quadilaterals yet
no not even that
it has two answers.
yeah it has two answers
br
Thanks
np
Daily calculation of area of famous logo.
Day 1.
This is a blueprint of a logo of a famous company.
In the blueprint, there was an error and it needs to be fixed.
Find the error in the blueprint.
Hence, calculate the area of the shaded region with the corrected version of the blueprint.
Turkish exams will be funny here
is trigonometry easy
VERY EASY FR MAN
🥲 
yesnt.
it's easy until IIt isn't.
Fr man
Geometry used by euclid
Ig it involves mostly the basic.2d shapes
And angles
Can someone explain exsimilicenters to me in simple language?
Help 🫠
where are you stuck?
Idk how to do irl problems at all
didn't the videos teach you how to do right-angled trig though?
I can do normal questions but when it's an irl one I just can't
So um
Is this sine?
no
which length of the triangle do they want you to find?
Um
Here?
But
Idk
😭
Cos then?
Cos 37??
Well inverse cos 37.
Is this also false? 💀
Did I at least mark the side right?
sin
Bruh he said it wasn't sin tho
Why is that?
cos = adjacent/hypotenuse
yeah
substitue value of cos 37
yes
yes
Okayyy
Omg it's right
Ok
Nahhhhh 😭😭😭 how in the hell am I supposed to solve these???
Is this tan?
Tan(6.6/10)?
Nvm
This is opposite/adjacent though no???
Wow um...I did it?
It was inverse tan!!
yes
So there's this
Let me think.
I'm gonna add a 3.5
At the end
When I finish the calculations
Right?
Opposite/hypotenuse
Sin 23
Sin23=x/4
Sin23*4=x
1.56+3.5
5.06
Is this correct??
Did I make a mistake somewhere?
Oh it was false.
Welp...damn it.
It was cos???
😭 how tf did I mix that up???
Omg I'm dumb as hell...
Hell yeahhhh I did this!!!
Ok guys I need your help 🙏 I want to do this last question right.
Use SOHCAHTOA
Is it the shaded
Tan?
Or the grey part
Wdym?
Is the whole right triangle
Opposite/adjacent no?
Yes
tan(59)=5/x
Just swap 5/tan(59)
Oops
Tan(31)*5=x
Is this correct?
nah
Okay can you explain why? 🧐
Then you multiply the x to tan(31) and divide tan(31) into 5
Where did you get the tan 59 from
90+31+59
4?
Why is it tan 59? Isn’t it tan 31?
Oh it’s a typo
Oh
That’s what I wonder too
lol
Damn
I made a mistake then
But can y'all explain why?
Uhhhh
plug 59 instead of 31
I mean 31 isn't adjacent, it's hypotenuse
yes
Use tan 31 =5/x and you get tan31x=5 and divide tan 31 to the 5 to get x=5/tan(31)
I'm trying to understand how 😭
Ohhhhh
One second
So from this
Okay
Are we not trying to find the yellow dotted line?
To solve its hypotenuse
I don’t think so… we should the finding the line like that’s in the ground (fully)
The line in the ground is 8.32?
Yeah… I think
Okay we can now use Pythagorean theorem
Right
a=5, b=8.32, c=?
5²+(8.32)²=hypotenuse²?
Yes
The following error occured while calculating:
Error: Undefined function sqr
Damn
This is my first time tutoring you geometry
How do I use the bot here?
,calc (5)^2+ (8.32)^2
Result:
94.2224
Ohh
Take their sqrt root
Gng why do we need the hypotoneuse
,calc sqrt(94.22)
Result:
9.7066987178958
9.70
Length on the yellow line
Okay.
Yellow dot
Line
So the answer is 9.70?
I think the question means the horizontal along the line
So ans is he slept in 8.32 m
Hmmm
8.32 m is the final ans
Yeah
.
Yes
Yep
The yellow dot wouldn't make sense lol
Yay
I did 2 on my own 2 with help that's not bad
What’s the work
Ye
That khan wants
Okay sure
Ok
Btw I’ll majority will be in algebra section
Help people that is in trouble of algebra
can anyone help prove LHS=RHS
Okay
try using 1+ tan^2 θ= sec^2 θand 1 + cot^2 θ = cosec^2 θ
ik the identities, i did use em but it got very confusing
show your work
mm.. that will be messy
trig trig trig trig
our trig has hints on exercise questions
and one of the hints is just
"see example 3"
like what
😭
just show it here br
Can you foil that
start by putting 1+tan^2(theta)=sec^2(theta) and 1+cot^2(theta)=cosec^2(theta)
Can someone help me
its quite simple basically all you need to do is
first convert into sin cos [as the rhs is in sin cos form]
then solve the fraction
you will end with something like sin4 + cos4/sincos
convert the sin4 into [sin2]2 and same with cos
and use the identity
and the answer should come
[hint separate the fraction at the end]
ohh alright thankss!
thank you
Anybody up for helping me please?
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
You can use Menelaus' theorem for ABC intersected by DE and the fact BD=BE.
https://en.wikipedia.org/wiki/Menelaus's_theorem
we have not been tought that yet in grade 10
just look up its proof and apply it to your problem. It fits grade 10 pretty well
I tried the solution. Is this correct tho?
I would draw CG parallel to AB.
But the same concept right?
because you don't need DF in your formula
Where is DF?
yep, drawing parallel line and using similarity is a standard way to prove Menelaus
in your intermediate formulas
basic proportionality theorem
What is the least amount of equations needed to contruct a perfect donut in a 3D space?
This is the improved version @upper echo
Bruh
1
Can you write it?
I have been struggling to do the last geometry problem, i need some assistance and ideas to keep going but i have found nothin so far.
Given a circle (O; R) with diameter AB. Draw the tangent line Ax to the circle (O). Let C be an arbitrary point on the circle (O) such that AC < BC. The tangent to the circle (O) at C intersects Ax at D.
a) Prove that the four points O, A, D, C lie on the same circle (are concyclic).
b) The line passing through O and perpendicular to BC at M intersects the line DC at E. Prove that OM \cdot OE = R^2 and that BE is a tangent to the circle (O).
c) AM intersects the circle (O) again at a point N (N \neq A). Let K be the midpoint of EM. Prove that B, N, K are collinear
If anyone is free, i will be very appreciate to hear some thoughts about the problem, thanks.
that's obvious
fair enough
Thank u so much 😄 i think i did overcomplicate the problem a bit 😅
if cosecA - sin
fu
wait
if cosecA - sinA = a^3 and secA - cosA = b^3
prove that a^(2)b^(2)[a^(2) + b^(2)] = 1
my mind is blank.
i tried to like. simplify cosecA - sinA and secA -cosA into cos^2(A)/sinA and sin^2(A)/cosA repectively
then took the cbrt
then like.
whta do i do
you mean this?
If $\csc A - \sin A = a^3$ and $\sec A - \cos A = b^3$, prove that $a^{2}b^{2}(a^{2} + b^{2}) = 1$.
oppenheimer
ye
wait csc means cosec?
yeah
huh
go on
substitute
after substituting and simplifying. It becomes (sinAcosA)^(2/3) [(cos^2(A)/sinA)^(2/3) + (sin^2(A)/cosA)^(2/3)]
ok no i got it
why was i worrying about this again 😭
👍
a^(2)*b^(2) = (ab)^2 right?
i forgot basic identities and have to double check
😭
ye
yes
Express a^3 and b^3 in terms of cosA and sinA and divide them. So, you get b=a*tan(A). Then just substitute it into that expression with a,b
Yeah they're the same thing.
I mean I did it from aan easier way bubut this works? Thanks ig
HHuh
Given quadrilateral ABCD. E,F are midpoints of AC,BD accordingly. Prove AB+BC+CD+DA≥AC+BD+2EF
Yeah
alr br how do you even. 😭
YYe but
how does one decide that from one. ONE question
😭🙏
dk tell me that the next time I see u
nah I'm like.
saving the link to this message so I ping you with this message whenever I see u online.
All wrong
💀
jk
What do you think?
I think radius is 2?
Ok it was right
How's this?
(x+2.3)²+(y)²=36/49?
looks right
Find an example of two triangles $ABC$ and $XYZ$ such that $AB : XY = BC : YZ$, $\measuredangle{BCA} = \measuredangle{YZX}$, but $\triangle{ABC}$ and $\triangle{XYZ}$ are not similar. (EGMO by Evan Chen, problem 2.2)
OSHOHAY_BALOK_:(
I can't find any
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
I don't think it's too hard
I think I overcomplicated this too much :((( I was trying to visualize a 120 degree rotation but I couldn't, ultimately only a 360 degree rotation would be a rotational symmetry because one of the side lengths isn't the same as the others. I spent like 30 minutes trying to solve it.
I suppose that one way to imagine this for myself intuitively in hind-sight is that I know that if a square isn't turned in divisions of 4 of 360 degrees or just respectively 90 degrees 180 degrees 270 degrees and 360 degrees that it won't be symmetrical, and I think that an isosceles triangle shares at least 3 vertices with a square right? So if it's not turned like that then it won't be symmetrical and because 180 doesn't work because the vertex of the right angle or whatever it's called wouldn't have another vertex where it would switch places with to become symmetrical.
alternatively, identify the corner that has two sides of equal length attached to it
theres only one kind of point like that in an isosceles non-equilateral triangle
if it had any rotational symmetry, there would be more of those points, which isnt true
or, that point is the center of rotation, which when rotated shows the shape has no rotational symmetry whatsoever
Thank you, yeah!
np
For an isosceles equilateral triangle, would rotating it 60 degrees by any multiple such as 60x2 make it rotationally symmetric?
120 degrees
not 60
I see, thank you! 🩷
np
Yeah that makes sense!
I assume a shape with 6 vertices or just a hexagon would be able to do that?
yea
Wow, thank you. That's really cool!
If you shear a parabola, does it always remain a parabola?
yes
That is so weird
Seems like no linear transformation can transform a parabola into a non-parabola, except the obvious edge cases of scaling by a factor of 0, or some kind of "infinite shear"
You can verify it algebraically tbf
Wait
Here $\frac{BC}{YZ} = \frac{3\sqrt{2}}{2}$
OSHOHAY_BALOK_:(
Nope, just count the cells
BC is a diagonal of a square 6x6 cells, YZ is the diagonal of 4x4. So, BC/YZ=6/4=3/2
I saw
But what about the distance formula
that shows this
BC= 6\sqrt{2} and YZ=4
Ok, use it, and get the same ratio
YZ=4sqrt(2)
It shouldn't be this simple😭
wait, wth is wrong with me, I just added 2 and -2 instead of subtracting
tnx and sry
but yet
They said Directed angle will fail here, that means normal angles must work
but you used 45 in both cases
Whatever tnx
I don't know, there was nothing like that in the statement.
not there, while stating similar triangles properties in the previous section of the book
Well it did use directed angles
Oh it worked maybe bczz its not SAS but SSA
Ssa is a thing!?
SSA is not true in general
but when you have a >= b, then SSA really does imply congruent
Can I get an example of such case?
the picture explains it
sorry it's a bit small though
Oh wait yeahh now I get it , ty :)
Nah np :)
$$
\text{The vertices of a triangle are }
A(x_1,; x_1\tan\alpha),;
B(x_2,; x_2\tan\beta),;
C(x_3,; x_3\tan\gamma).
$$
$$
\text{If the circumcentre of } \triangle ABC \text{ is the origin and }
H(a,b) \text{ is the orthocentre, then } \frac{a}{b} \text{ is equal to:}
$$
$$
\text{(A)}\quad
\frac{\cos\alpha+\cos\beta+\cos\gamma}
{\cos\alpha\cos\beta\cos\gamma}
$$
$$
\text{(B)}\quad
\frac{\sin\alpha+\sin\beta+\sin\gamma}
{\sin\alpha\sin\beta\sin\gamma}
$$
$$
\text{(C)}\quad
\frac{\tan\alpha+\tan\beta+\tan\gamma}
{\tan\alpha\tan\beta\tan\gamma}
$$
$$
\text{(D)}\quad
\frac{\cos\alpha+\cos\beta+\cos\gamma}
{\sin\alpha+\sin\beta+\sin\gamma}
$$
BlackidoZΣ
a/b is equal to?
Recall that for a triangle $ABC$ with circumcenter at the origin, we have that $$\overrightarrow{OH}=\overrightarrow{OA}+ \overrightarrow{OB}+ \overrightarrow{OC}.$$
Civil Service Pigeon
Help
Prism is base area times height
Let me think
1/2*49π
*20
24.5π
*20
490π
LOL I JUST SUDDENLY GAINED INSPIRATION AND SOLVED IT ON MY OWN NVM
Peak 🗣️ 🔥
1/3*3.14*4*10
Right?
Times 3/4
Dangit I got it wrong...
Rip.
I was afraid they'd ask real life problems
And they DID.
I have to overcome this...
How tf...
Do I just add the values together here?
1/3bh
Base is
,calc 64*64
Result:
4096
uhh yuo should js use formula find overall pyrmaid and just subtract the other pyramid
Oh
Let me see
4096*48?
(Times 1/3)
Yep
.
1/3 times base tims height
Yeah
yeah and then
.
shld be?
Ok
4096 cos 64^2
Multiply by 48?
yes
Ok
and then subtract the other pyramd
Result:
1.96608e+5
Check this
But 1/3?
Plus you gotta multiply by height.
Result:
256
so
,calc 256*12
Result:
3072
Yupp
u subtract
3072/3
,calc 3072/3
Result:
1024
Result:
64512
Huh
1/3 times 12^2 times 12
16
Lol dw
you get 63936
Really?
.
65536-(16^2x12x1/3)
you should be write
Dw gng
and that shld be answr
Lmaoooo
Yeah man thank you.
algs man take care
It was right
eyy lesgo
👍
36^2
Times 36
/3
15552
Umm
15552*0.75?
DAMN it was wrong
RIP
Ahhh I want to be able to do it on my own man
Ah damn. I found 11664 right but
I forgot one calculation...
😭
1/3*10^3
333,33...
2 cm from the top...
So is it 8 cm??
I found 120
But it's false???
333-213 bruh...
Oh damn. The length was also 8...but why?
You mean the side length of the base square?
Yes
The square side length was 8
Well try visualizing it
how could the side length of the base square be the same?
Try imagining you filling up the inverted pyramid with water
and stopping at 8 cm
So I found a 54.
There's a semi-cylinder...
What the hell is the radius here??
3?
Damn
what's your definition of radius of a circle
yeh
Ok
It's also half the diameter right? So if you can find the diameter, radius is just half of that
Yeah
4.5?
My last guess
don't guess
😭
stop guessing
Bro 9/2
just look at the picture and think 🙏
why 9?
How is 9 the diamater of anything 🗿
9 doesn't have anything to do with the (semi)-circle
Just take it slow man
Idk
Right
Is what 3?
The side length
You're asking about this red line on top?
if you mean the top side of the rectangle,
the length of that line (that i've highlighted in red) will be 3m
(note that this is not the radius of the (semi)-circle)
Ok
So at least I got the 3 right but how do I find the radius?
it may help if you complete the full circle
and identify what type of line you've just determined the length of
yes
no
/2
no
Semi cylinder
😭
Why not
well you'd want to divide by 2 because you have a semi-cylinder
but you made a mistake before that
π * 2.25 * 2
why multiply be 2 there?
i.e. why did you use 2 for the height?
has got nothing to do with the semi-cylinder
Not
😭
Ok
How do I find the height?
We only have a 1.5
That is the radius
Idk what numbers we can go off of rn.
The height is given in the picture
🤨
don't think of "h" in formulae as vertical
consider the direction you'd extend that semi-circle at the front
to get to the other semi-circle
9??
yes
you shouldn't be guessing
It's not about guessing
It would never cross my mind man
its about recognising what each variable represents in formula
and don't forget to divide by 2, because you have a semi-cylinder
Then divided by two
Yes
Can I do the calculation with this bot? Let's see
,calc π*(1.5)²*9
The following error occured while calculating:
Error: Syntax error in part "²\*9" (char 8)
Rip
Result:
6.2831853071796
Oh
not the unicode pi
No
Don't 🗿 me bruh
Fine I'll do it there as well
Result:
31.808625617596
There we go
Is the rectangular prism
54 at least?
I can't believe I'm failing miserably at this 😭
You're not failing, you're learning
Ok
So do I just add these two together?
Ya
Bro this is so hard 😭
I'm absolutely cooked I can't solve these problems...
So...base area times height
1.2*x/6
?
Wait wait wait.
1.2x/6>1.2y/4?
If this isn't the right way then idk.
It's definitely incorrect...yeah.
Hi
Yeah
I always suck at problems
alright, let’s start simple and define variables.
Ok
Yep
alright.
Dw
We have $6$ fish, and we need $0.25m^3$ per $1$ fish.\
In this case, how many $m^3$ are needed for $6$ fish?
WanderingFurr
(i’m still new to TeXit so sorry if i screw smth up lol)
1.5?
alright, how’d you get that?
I found 1.5 already but not sure how to use it.
.
One moment.
This gave x>1.5y
Ok, so we now know that we need $1.5m^3$ of water.
So, how do you find volume?
Base area times height
WanderingFurr
Think you can solve for h?
1.25?
I would believe so
And the unit of measurement is..?
m³
Ok
Is it?
$1.2 \times 1.25 = 1.5$
WanderingFurr
I would say so.
Okayyy.
A fish tank of base $1.2m^2$ can fit $6$ fish in with $0.25m^3$ per $1$ fish given that the water is filled $1.25m$
WanderingFurr
Right.
That’s how you would answer, as this is a worded question
worded questions always require worded responses
so keep that in mind on exams
So the answer is indeed 1.25 meters³?
Okay
Not cubed, as we’re just talking about height here
Right right
$1.25m$
WanderingFurr
the fuck-
bruh alright let’s hear it
It happens a lot with me
Give me one sec
Take your time.
1/3bh?
-# still trying to solve it myself..
Pyramid volume
I already compiled a small list but I want to see what you find
Height=x