#geometry-and-trigonometry
1 messages · Page 84 of 1
for us in grade 9, we can choose to do math 10
oh actaully?
I dont know if ill be much help though
you might need to work with an expert since I recently just started this
good luck though
same
the fraction and the sin part is kinda hard
<@&286206848099549185> help us
oh opposition/hypotnuse?
i don't see any negative signs
like are you trying to find the angles or the side lengths of the triangle?
Right, but COT can also be in Q4
Which would make both X and 1 negative
Tan*
or at least
1 is negative
And x as a value is negative
Which would make sin of that also negative
If you draw out the triangle
if it is in Q4. yes it is negative. If it is in Q1 then it is positive.
you made a valid point there
both
how do i do this .-.
i kind of remember you multiply everything by the demonimator
but after that i forgot
$\frac{4 \cdot 2 + 4i \cdot 2 + 4 \cdot 9i + 4i \cdot 9i}{2^2 - (9i)^2}$
then remember that $i^2 = 1$
south
so the cycle repeats every 4 powers
so if I had like $i^{11}$, well that's just $i^4 i^4 i^3 = 1 \cdot 1 \cdot -i$
south
that's how it works, so just divide your number say 11 by 4, and take the remainder
np!
My brother Taught me a method that if you divide any number by 4, and if it ends on .25, it’s square root -1, 0.5 -1 , 0.75 -i , 0.0 1
I think it works
But not sure
that comes out to be the same as taking the remainder (since .25 = 1/4 means a remainder of 1, .5 = 2/4 means a remainder of 2, etc)
Ig it does work
okay cool, thanks
My current progress with this question:
I figured PA×PB=PC×PD and then put the values which resulted in:
|z0-a|×|z0-b|=|z0-c|×|z0-d| and squared both sides and expanded a lot
Final result got a bi-quadratic where I let z0=x
Found that the sum of the roots of the equation divided by 2 is the exact same as the RHS to be proved in the question
What should I do now?
Hello, calmest. I think I can help you to solve this problem.
there is one unique point where CD and AB intersect (assuming that CD and AB aren't parallel)
hence the roots of the biquadratic should be the same
and $2z_0 = \text{sum of roots}$
south
Wait so all of them to be same?
Oh
Nvm
Hm
Can you please elaborate because I don't fully understand
two non-parallel lines always intersect at one unique point
hence there can only be one value of $z_0$ that satisfies the biquadratic
south
Ohhhhhhhh
That makes a lot of sense
So 2 roots of each line are there to make it possible
Thank you so much omg
I've been stuck in this question for days
But so if all roots are same shouldnt it be 4Z0?
no it's just $z_0 + z_0$ = sum of roots
south
no, z0 is just the intersection of the lines
hmmmm
Oh wait nvm
I took Z0 As x
So only z0 is possible
But then it still doesn't make sense to me
This one is not too difficult if you know the equation of the line in complex numbers.
Yeah no I solved it
I reviewed my notes and found that writing the 2 complex slopes of the lines and subtracting them gave the answer
On the surface of the planet lives one inhabitant, that can move with the speed not greater than u. A spaceship approaches to the planet with its speed v.
Prove that if v/u > 10 , the spaceship can find the inhabitant, even it is trying to hide.
This is geometry right?
Could anyone try to explain gr 12 trig identity’s? I’m very lost
Be more specific
Could anyone help me with angles of triangles
Hmmm?
Wdym?
Like
Idk how to explain it but thats what the assignment is named
Its finding missing angles and the triangles are complex
and like triangles in real world stuff
Okay, show me an example problem
I used ai to solve them ignore that I got it “correct” but I wanna go over them to actually understand it
Okay 👍
Small chance I may not know how to do it though. I'm in algebra 1 in terms of school, and my knowledge is pretty scattered past that
its alr if u dont know it
I’ll post it here js incase anyone knows it if u dont know it
Gimme a moment. I know I can solve the first one
the one with a lot of boxes?
Oh, yeah
Nvm I see what you meant
Yeah, that one
For angle 2, it would be 130°+30°+x°=180, since it's a straight line below, and any full turn around that equals 180°, so angle 2 =20°
Same with angle 7; 110°+x°=180°
So angle 7 is 70°
And you can find angle 5 with either the known angle opposite to it or angle 7, either way, you get 110 (opposite angles like 110° and angle 5 are always the same.)
Now, with the triangle formed by the 30° angle, angle 4, and angle 5, you can find angle 4, since we now know angle 5 to be 110°
Triangles interior angles always add up to 180°
So 110°+30°+x°=180°
X=40
Do you understand how to do it so far? @round void
Oh, and question 15. As said earlier, triangles interior angles always add up to 180°
So you add up all of the x's
You get 2x+3x+4x=9x
So 9x=180°
And x=20°
So you just plug in x as 20°, and there's your answer
And question 26. As I've said several times already, triangles interior angles always add up to 180°
So 72+77+(angle 2)=180°
So, it seems it's actually not drawn to scale, and angle 2 is 41°. As for angle 1, I need more info
Assuming the cars roof is ignored, it would be 41°+(angle 1)=180°
So in that case, it'd be 139°
But I don't know if that's what it's asking.
@round void
As for question 12, it's just time consuming, but basically, here's the 3 rules you NEED to know. Opposite angles in intersecting lines are always the same. Adjacent angles in intersecting lines always add up to 180°. A triangles interior angles always add up to 180°.
You can find the answer to all of those questions if you know those 3 rules.
I'm too lazy to finish the one with all of the boxes, it's super time consuming, and I get bored kind of easily. Not to mention I do math for 88+ minutes a day.
Sorry
Np, just memorize these rules
No matter the shape or how weird the triangle is it will always add up to 180?
Yup 👍
Wait what is adjacent angles again
One sec, I'll send a pic
1 and 2 are adjacent, 1 and 4 are adjacent, 1 and 3 are opposite.
So like on opposite sides of the line
(Sorry it's sideways, didn't notice till it was too late)
Okay, gimme a moment..
Just to reinforce this, it doesn't matter the angle. 1 and 2, and 1 and 4 are still adjacent.
1 and 3 are still opposite
So long as the lines are straight through each other, and there are no turns, those rules will always apply
If you still don't understand, tell me. I'm not mad or anything, I promise. I enjoy being able to succeed in helping people
@round void
So if they like cross eachother
kinda
I kinda see it and I kinda don’t see it
also when ur looking at stuff like that which side of the line do u know the number correlates to
like how the 1 is in between 2 lines
which line would it be
Oh... you thought I was numbering the lines?
nono like
The numbers represent angles
Yes
I always saw it as like the line being numbered
Not the actual angle, but like a variable
So all of those numbers in the screenshots you sent are essentially variables
Unless it had the degree symbol
Or the (2x) ones
Do you understand it now?
@round void ?
Yea
Yay
help
i got everything but d
im just not getting the right answer
what am i doing wrong pls help
They said beta is between -pi/2 and 0
I.e the fourth quadrant
Where tan is negative
So your tan beta would be -1/2 and not 1/2
Also you shouldn't write it like this
wait how should i then
Tan^-1 (3/4) and tan^-1(-1/2)
oh no wonder cuz i drew my traingle in quadrant 2
wait let me do it and show u so u can tell me if its right
Wow
This explains why cos and sec are positive in fourth quadrant
Dang
I thought they took it as a convention
idek whats going on
Lol nvm
i do fine on all of them besides tangent
the 1 in negative right
is*
omg
thank you im so slow bro
i didnt realize the 1 had to be negative
okay wait so what abt thisone
why is the image 12 mb 💀
ask my cell phone
u literally can just tilt ur head
you dont have to worry about alpha since they already gave it in tan
as for beta
which quadrant is it present in ?
.
🔥
then 1
can u stop being mean
damn
yes the first quadrant so tan would be ?
positive
you have cosbeta as 1/2 so your tan beta would be ?
its sqrt 3\
why -1 ?
if it was cos\theta = -1/2 then you would be right but that is not the case
well i got all the other ones right so why is this one not working
where?
i boxed them
why assume ?
cuz it goes in q4
which one ?
oh wait but do i not do that since cos isnt negative there
but the 1 here is horizontal
?
is that right
yes
i am doing something wrong
💀💀💀
this is the answer btw
oh should i have done the 3 denominator first
this is you rn
DUDE i am losing my min d
i erased it
i cant do algebra i surely cant do crypto
can you please write it and show me how to do it
so where did that 9 come from
i multiplied and divided the whole fraction with -9
but why
did you just think "oh i like this number" and did it
lol no
@obsidian harness
ah the 9 comes from the denominator, 16sqrt(3) / 9
generally you want to multiply top and bottom by the LCM of all the denominators
so i took the 9 out of the -16sqrt3/9 and just distributed it to everything
take*
yall r too smart for me i cant\
Help
Circumference is minor arc + major arc, and then you can solve for r by using C=2pi r.
then i would suggest drawing a triangle to find the angle.
Is this a geometric series question?
How to find the equation of the ellipse which is formed by the intersection of the cylinder of x^2 + y^2 = 1 and the plane x+y+z=1 ?
i moved z from left to right side and sqaured it on both sides
and substituted x^2+y^2 =1
leaving me with 2xy=z^2 - 2z
is that right /
?
what to do adfter tha t?
Is this related to volume and area?
1/3 x pi r² for cylinder ig
@upper karma
i just want to find the equation of the ellipse
what shape is the ellipse
its in 3d ._.
what about
<cos(t), sin(t), 1-cos(t)-sin(t)>?
0<=t<=2pi
:>
the equation of a line in 3d is usually parameterization 😔
i dont know if you can like do it without parameterization at all lol

.
you parameterize.
got it ty
Did you use elimination method to solve it?
Linear inequalities in 2 variables
is this correct?
Isn't a circle sum up to 360⁰?
We know that EF and BF both have the same angle
(180⁰-48⁰)/32⁰ = 66⁰
@gloomy osprey
E and f aren’t the base angles right?
nah, just the standard method of parametrization
No
don't see anything wrong with it
Not trying to sound dumb jsut trying to process it I thought cus the alternate angles equal the same and then the base equal the same so the remaining angle is the difference
Is he jsut trolling or smth
me?
Nooo
oh sorry
The other guy who said it’s 66
B amd F are
They not?
Mb i misunderstood the concept
could you elaborate further on this?
I applied lines and angles formulae on this
I just want x 😭
180⁰-interior angle
x = 84
❤️
(n-2)x180⁰ = x?
48 + 48 + x = 180
In the graphics, A, B and C are tangency points. calculate 𝜃
Ik the triangle with theta in it has 45 as one of the angles I just need the other
See why can’t we do stuff like this in my geometry class?
thoughts anyone?
How do you solve this
Pythagoras gives you the lengths of DC and DA
or distance formula, same thing
i did that i used it
for some reason they dont take 4 root 10 times 40
nvm i fumbled it
use distance formula
guys if we have a right triangle ABC in A
and we draw E the orthogonal projection of point A on (BC)
does this prove that the triangle AEB is right-angled at E?????????
uh yes?
really?
by orthogonal projection you mean the altitude right
well yea
in this case it does mean that according to a quick google search
ye the altitude of E
tho doesnt the concept of triangles in itself break when you start to get to vectors stuff
yea then obviously by definition of altitude
no there is no vectors stuff
in this case
then yea
anyone can help?
thx
Start by joining bc
after joining BC,
α=2<ACB
β=2<DBC
<ACB=180-90-<DBC=90-<DBC
α+β=2<DBC+2<ACB=2<DBC+2(90-<DBC)=180
according to cyclic angle theorem
I think 72 but not sure
why is there a square root before the 12^2 + 4^2
shouldn't it just be 12^2 + 4^2 which is 160
and then the square root of 160 is 12.65
then you multiply that by 6.32
and you get 79.948
which is basically 80
cuz there is no need to do 1/2 (80)
cuz this is rectangle
are for rectangle is simply l x w
you calculated as if the shape is a triange
agreed that there shouldn't be a 1/2 being multiplied by 80
but why are you rounding
why are you rounding early when you can get an exact answer
well
I guess not rounding would have been better
but even though I rounded I still get 79.948 and then I can just round again
rounding early isn't ideal but it still worked
I got 49/48 but the ans key says 64/15 can someone verify the answer
b = 7 a = 83 right?
49/48 is correct
ay guys any idea on how to do this
i need to make a diagram and its trigonometry
so is this like a 3D shape
Can y'all help me with this? Honestly I was enrolled into school really late, hardly know anything about geometry and am trying to get extra credits. Any help would be great 👍🏾
All I know is that the first shape's supposed to be a kite, the third one's a rectangle and yeah
Thanks
Can someone explain this to me and how to make it a decimal
looks like a rectangle with the coordinates listed, past that there's not really anything to say without more info
ahh
assuming it's a rectangle, you only need to find the length of the sides AB and BC. The way I think of them is as the hypotenuses of right triangles
like this, so then I'd find the length of these legs here
I finished all those stages and i was left with two root numbers with different radicals
I was wondering how you make that into a decimal
Prove that You can always pose a circle of radius S/P inside a convex polygon with the perimeter P and area S.
How do I start learning trigonometry as a 13 y.o with no experience?
use area = base*height for a rectangle
Khan Academy
and org chem tutor on YouTube
why org chem?
khan academy better tho
Could someone help me with this pleaseee it's stereometry
At least the first problem 😮💨 it's asking to calculate the volume
I've got it now 😭
guys A F and C algebraically should be aligned but even in the 3d visualisation it doesn't look aligned got any idea?
note that no measures were given for the ABC triangle
<@&286206848099549185> \
The attached diagram shows a regular pentagon and a regular hexagon. It is not drawn accurately.
Work out the size of the angle marked x.
4 marks\
Can someone help explain how to choose what x values to use for function plotting tables?
someone pls draw on this and work it out
can i progressively do this and someone help check my answers along the way
for number 1 i got the perimiter of the playground to be 273 yards=819 feet
so i divided 819 by 50 to get 16.38 = 17 rolls
and that 17 x 90 = 1530 is the cost of the fencing
final answer i found for 1 after finding grass stuff is 2682
Are there any textbooks or free sources that help with proofs
how do i do dis
oh i hate planes
you don't know how to do it?
i slightly remember it was a rough year when i did algebra
do you have any friends that know how to do it?
is a plane always 4 points?
no
how many points does it have to be
more so each plane is like a wall
its a infinte surface that extends in all directions
ok
and you want to find the planes that the line ab lands on
so
so you have the left wall
and the celing as planes that contain line ab
im kind of confused
ok
um
oh ew
ok
each side of the cube has a plane
the plane is the light bluee area in this picture
you want the planes where your line is on both
Can someone please help me with question number 2?
Represent z_m=z0+w*z^m, where w is some nonzero complex number and z is a primitive root of degree n. Then expand binomials and change the summation order. Use the fact that z^j+z^(2j)+....+z^(nj)=n, if j=0 and 0 otherwise, for j<n.
could someone please help me showing that ABC~A'B'C'
Wow that is something I didn't expect to be using. After using that method I managed to reach the answer. Thanks!
do you know the internal angles of regular polygons?
Nope
well the angles add up to (n-2)*180
then you can further divide by how many corners there are
How am i supposed to calculate the surface of this shape??
count the squares
A regular polygon P has n sides and lies in 2d cartesian plane. Find all possible value of n if all vertices of P are a lattice point
Any hint?
I suspect that n must be even
does a triangle work? A square? A pentagon? A hexagon
This is a classical fact. Only squares fit. https://hrcak.srce.hr/file/2836
hi! Is there anyone who can help me on this
is there a specific question you need help with?
well iim very stressed bc its my last year and they gave me geometry and pre calculus at the same time ad they gav eme pcakets to do these math and i jst need soemone to show me how to do tuis
or if i did smth wrong
alr let's go one by one
oh noo :((
if i did it rigth
let's just take it slowly and make sure you understand
so i jsut need someone who knows geometry :(
ok so for the first question is it asking you to find all the angles?
okay!
its something like that
ok
32 is correct for that one gj
ok so
do you see the angle directly opposite of that one?
do you know what that kind of angle is called
for the first one?
yes
i do know that with the square it's rigth angle
it's called a 'vertical angle'
ohh
:3
if you have two intersecting lines, the opposite angles will be equal
so based on that, what is the purple angle equal to?
what do u mean by that?
the dark blue is the two straight lines that are intersecting
the two light blue angles are equal
ohh
like the angle measure?
ohh
it would be equal to the opposite angle, so 32
it's ok lol
so i write 32 in thathat angle?
these two orange angles are equal
180-3180-32
they are also vertical angles
so it would be 180-32
yeah
because 180 in a line right?
No!
would it be 180?
ohh
yes
wdym by that
like
ahh lemme. Thjnk how to say it
so everynumber we see i just have to put "180-#" with the number
this is only the case for a straight line
ohh
i got 55
yes gj!!!
in the triangle above, what is the total angle sum?
for the entire triangle
how do you do that again
ok so for any triangle, the total angle sum would be 180
the sum of these yellow angles would be 180
for ANY triangle
yes,!
you know the total sum of the three angles is 180, and the other two are 91 and 55
89?
so you would calculate 180-91-55
good job!!
yes!
ok!!
no, the total angle sum for the line is 180
if you know one angle is 91,
the other would be 180-91
so in this diagram, the yellow angles sum to 180
64?
since you knwo that the total angle sum in a triangle is 180, can you find the light purple angle
really close
the light purple one
it should be 180-89-25
yeahhh
just subtracting the other two angles from the total
i got 66
good job!!!
:))
now we got this
can you find the magenta/pink angle?
OH WE GAVE MORE?
loll
yes!
i think you should be able to solve the rest with this knowledge
ping me if you need any help tho!!
yes
Okay
I got 180
Wait
Do I add of all of the things we put the numbers at
@floral sun
Only the ones that are in the corner?
you dont' need to add any angles together
no you don't need to add any angles
Then how do I know what I put in it
you dont' need anything else for that question
i will ;DD
If you're fine with the fact that I am currently learning trig in my own time, then sure.
what
grade
I know a pretty large amnt so far. I use kahn academy
are you?
8th grade
you'll be fine
i might just cry
i can tutor u
I learned a tiny bit of calculus too (why I'm learning trig)
dude i know its not always the teachers fault but this teacher is geniuny terrible
Damn
she just explains one lesson and immediately moves to te next one with no practice or no info in how it actually works
damn that's bad
i have a test on thursday
i shouldve locked in earlier but i had other grades too
now or never i guess
wait dm me topics or soemthing
Look. If I were you in that situation, I highly recommend you use kahn academy. It's amazing for math.
I just need to pass and ill try to get abetter grade on the next semeseter
aops is rly rly good
What is aops
art of problem solving
Can someone help me with this please
which ones
somebody help
try dilating each point on the triangle
so (-8, -8) goes to (-2, -2) for example
Can someone please tell me question 1?
The number 1 is 50 degrees
Nvm, for a sec I though I was wrong (why i deleted the messages.). I was right though. 302°
For number 2
Oh.. wait.. we're supposed to find the arc length, not the angle
It says measurement
You sure?
yeah the measure of the arc is the degree measure of the central angle
if they wanted arc length they would've stated it directly
Can someone please tell me question 1?
consider $z_1^2 + z_2^2 = r^2$ which implies $z_2 = z_1 e^{i \theta}$
south
Hm
Yea
But what after that
Now we have theta in the mix
I attempted the question again and again and found that (z1-z2)^3=40
$z_1 (z_1^2 - 3z_1^2 e^{2 i \theta}) = 10$ and $z_1 e^{i \theta} (3z_1^2 - z_1^2 e^{2 i \theta}) = 30$
hmmm
south
interesting
Literally just added those 2 equations
Hm
$\frac{1 - 3e^{2 i \theta}}{3 e^{i \theta} - e^{3 i \theta}} = \frac{1}{3}$
Hmm
cause everything has (z1)^3
Yea
wait I fixed it and it got wrose
,w ((1-(e^(2ix)))/((e^(ix))-(e^(3ix))))=(1)/(3)
well we have
$z_1^2 + z_2^2 = \frac{10}{z_1} + 3z_2^2 + 3z_1^2 - \frac{30}{z_2}$
south
by rearranging the original equations
idk
There is the fact that Im(z1^2+z2^2)=0
So either both of them are real numbers or their imaginary parts are same
I'm guessing the later
$z_1^2 + z_2^2 = \frac{1}{3} (z_1^2 - \frac{10}{z_1}) + \frac{1}{3} (\frac{30}{z_2} + z_2^2)$ also
south
3a^2 + 3b^2 = a^2 - 10/a + 30/b + b^2
a^2 + b^2 = 1/2 (-10/a + 30/b)
yeah you get the same equation either way
I think there must be something to do with the Im(z1^2+z2^2)= 0 thing
yeah I think z1, z2 are real or something
,w a(a^2-3b^2)-b(3a^2-b^2) simplify
Hm
What
Oh
L
I think the question is wrong then
Well
I have a question related to P&C
I'm not sure if my answer is correct
Question 3
I did summation of n^2+r^2-2nr with r=1 to n which gave a cubic of n and got exactly n=9
As a solution*
Oh
hi
@obsidian harness Alright I got my math test back
the linear programming problems were correct
I actually ended up with a 76/71
now look i don't pretend to know math but uhm
hmm
if you have 71 points available
and you got 76
the math aint mathin

💀
Extra ptss
I need help with trig identities
Guys how do you visually tell the difference between opposite rays and lines?
I know that opposite rays have the same end point while lines go on forever, but they look the same to me.
WHAT AM I DOINF WRONG HERE ITS SOMETHINF WITH MY NEGATIVE SIGNS BUT IDK!!!!
for b,d,and e i literally got the right answer besides the fact its + or -
what was (b) asking for
ik the answer jst how do i solve it
Wow good on u
Out of anyone.... GPT???

Ah you were so close
Should have known to investigate that idea
yo where did the 5pi over 4 and others come from?
these are notes from my teacher i just dk how he got them
Tan is periodic every pi
thats 2theta when tan(2theta) = 1
So tan(x/2) is periodic every pi/2
But you do not need this fact if you let 2 theta = ....
why is it done 4 times if its asking for intervals between 0 and 2pi
wait i understand it now
im goated
why is q1 and q3 mentioned though
A consequence of 2 theta being in q1 and q3
You meant to ask why are q2 and q4 there right
no i understand that
its just that is that necessary to solving the question
also when would I solve for the quadrants only in comparision to each period like in the example I showed
for ex, why did we solve for all the periods in (a) and just focused on quadrants everywhere else
soh cah tuah
ah cause you have $\cos x = \pm k$ for some real number $k$
south
so that must cover all 4 quadrants
automatically
same for $\sin x = \pm k$ or $\tan x = \pm k$
south
may someone prove it why x = 35*?
more context?
only this information
then there isn't enough to determine/justify what x is
i think so
i tried to prove it by describing a circle around a triangle
but couldn't solve till the end
there's nothing fixing the position of R,
the triangle can be rotated about point Q
giving infinitely many possible values for x
oh ok
in original problem asked "find bearing of R from Q", i drew a vertical line from Q and then couldn't prove that x=35
Apparently the problem statement is incomplete
Hey guys, do you know where can i find hard high school math question online
Any recommendations??
Art of problem solving contest collections
yes it's incomplete
you can keep Q fixed and rotate R anywhere you want
Thx for help bro
Calculate the field of the figure painted red
are they right angled? and are the two vertical lines parallel?
if yes u can use similarity
Yes
okay so the smaller right angle triangle and has 2 sides, 3 and 5 as the hypotenuse
so the remaining side is 4
now u can use similarity to figure out the height of the larger triangle
,w 3/(5+3) = 4/x
Ok, thanks
alg
Hello
What s the best geometry book you ve read(looking for an advanced technique book)
It solved the question better than wolfram alpha 💀
idk if yall see that but this is so difficult
I guess 4.8z 5.6 z and 7.6z
yes hes riht
You found out the value of z?
What
i dont know what z is
Its a variable/unknown if thats what you are looking for
Cooked
ok
so
lemme cook
180
wait
no
180
180/5.6?
im fried arent i?
ima say
there all 180
?
im dorry bro
this is so confusing
😦
im done for
4.8/5.6/7.9?
no
those are the angles
right?
ohh\
do
i add the 180 add these?
4.8z+5.6z+7.6z=180