#geometry-and-trigonometry
1 messages · Page 313 of 1
to identify whether 10,24,26
is a triple you can apply similarity
divide all sides by 2 to get 5,12,13
which is a common triple
I added (Square Root Method) so I know there’s methods besides square root
And I added subscripts to Leg 1 and Leg 2 like u said uwu
no parentheses around the (2x)
@silent plank
AHHHH I fucked up, it would = 4x^2 right?
yes
2sqrt(6) wasn't squared properly either
@silent plank
The square doesn’t cancel it out?
the 2 would also be squared

I did nut know that
Well, it’s always lowercase in my notes uwu
for the problem below that you didn't write in the sqrt for the sqrt(61) in the first line
@silent plank
Omg
I’m glad that’s the only part I messed up on cuz the answer still remains the same
And about the baseball one it’s kind of a dumb question so ignored it but what would the answer be?
@silent plank 
yeh, mistake looks fixed
What about these two?
round answer to the satellite problem
Uhh
I have no idea what the square root of it is and we’re not allowed to use a calculator
factorisation i g
Actually this is old hw and he apologized for not noticing how big the numbers were, so I’ll round it yea
x = 2829?
looks like there's issues with 37
@silent plank
I see what I did wrong, but 4 sq root 5 is the b length right?
you should apply pythag twice
once for the altitude and a second time using that value to get x
couldn't be bothered checking every single one but looks like you got the idea
couldn't be bothered checking every single one but looks like you got the idea
@silent plank
Noo I meant just 37 cuz that’s the only one I changed
Ohh or do u mean u never checked all of em to start with when I first sent it? Cuz that’s understandable
yeh
yeh
@silent plank
How am I supposed to do this
determine whether the sum of the squares of the 2 shorter sides is less than, greater than or equal to the square of the longest side
Oh I know that, but how does he expect us to do this without a calculator
calculating the squares of these values is pretty simple
yup
WHOOPS
my dumbass was tryna find 3 sqrt 2 😭
Aight @silent plank last one for the day could u check these 😄
Oh actually I didn’t understand number 2 😔
parentheses issue again with Q1
Damn it
But then it’ll become three terms on side instead of two since there’s no like terms to combine
you'll have a quadratic equation
oo I see
as for Q7, you mixed up your identities
yeh,
first one is obtuse
second is acute
Are my signs right?
which signs
Greater than less than
I thought less than meant acute because smaller angle?
look up some visualisations online
Ohhh it depends on C not a^2+b^2
Understood
No factors of 1 add up to -2 >:(
For number 2 ^
you have the factorisation right there
-1 and -1 don’t = 1 😔
I need to find two factors of 1 that equal -2
OH WAIT
Ahhhhh
x = 1 alright
Everything fixed? 
Hi, could anyone work through these questions with me?
about the first question, you have to express y as 5-3x and put it into the first equation
about the second one, what about using graphs?
<@&286206848099549185> Can someone help me with Quantitative reasoning
@whole carbon you should first post your problem and only then ping helpers if 15 minutes went by with nobody responding
please tell me you're not coming back with the same problem sheet as last time
Mathematical logic
The middle column is correct
Also this doesn't belong in #geometry-and-trigonometry, it should be in #proofs-and-logic
What is your answer?
Yes
The answer to the third column? Or the truth table for 'implies'?
3rd
That would be wrong
What is it then
Its all T?
Yes
How do I solve for the horizontal shift?
Can I assume
that y=0 then solve for c?
Or is there an alternative way to do it
Wait thats to find a sine function to find a cosine, can I assume the highest point on a graph which is 7:12 or 7.2
what do you mean by swap
i don't know what you're talking about.
is there a problem you're doing? this could clear up what you're trying to do.
this does not help
what do you mean by "some calculus"? why are you refusing to post the full problem so i can figure out exactly what you're trying to do and how to do it?
oh boy, sideways
so you want to find x in quadrant 2 such that cot(x) + 2 = -tan(x)?
Is my V Window too big if I’m seeing a simple straight line?
I’ve double checked my trig functions
And they are all in radians
h(t)=2cos(pi/372(t+7.2)+9
what's the Y range of your viewing window
what's the Y range of your viewing window
@dark sparrow -10 to 10
yeah too big
the range of your function is [9,11] so a window which doesnt go too far beyond that would be better
say, [5, 15]?
hold up
it’s somehow still a straight line
period is mega huge
try making it like 0 to 600 or something
ok
Ohhh
Ok
Thanks!
I made it
0-2000 (that pic isnt a represensative of 0-2000)
might be limitations of the calc
If I rotate a line around its normal line, in a 3d space, do I get a plane?
But if I was given 2 of them which are normal that is a plane right
Yea
Great thanks
So I came acroos a geometry question where the basic setup is that you have 2 skew lines, both given in vector form, and a point M. You need to find a line that intersects the 2 lines and passes through point M. I struggled to find a simple method (I mean really simple, the method I used is still not particularly hard but I ended up with a peculiar system of equations where my calculator just couldnt figure it out if I didnt first solve for one of the variables and then plug back in so that it was a system of only 2 variables). Is there a simple method for these types of questions, or do I have to end up solving a system of 3 non linear equations (again not particularly hard but I wonder).
Basically my way to solve it was to take a general point on line 1 and line 2, then write the vector equation for the line you want to find as M + t(M-P) where P is vector for a geenral point on line 1. Then equate that with H a general point on line 2 and solve the system of equations for the three parameters (and in the end you only have to care about the solution to one of the parameters)
I need to review my coordinate geo, but here's what I can think of
Take any general point on the line 1 as $\overline{r_1} = \overline{a_1} + \lambda\overline{b_1}$
And on line 2 as $\overline{r_2} = \overline{a_2} + \lambda\overline{b_2}$
Now, on substracting,
$\overline{r_1} - \overline{r_2} = (\overline{a_1} - \overline{a_2}) + \lambda(\overline{b_1}-\overline{b_2})$
livvney:
This would give you a line intersecting through both the given lines,
And any general point on it would be given by $\overline{r_1} - \overline{r_2}$, which, you can just consider as $\overline{r_3}$
livvney:
Equate r_3 with the vector equation for point M and solve to get lambda
Is this channel free?
This doesn’t make sense to me, shouldn’t the side that says 189 be the longest side?
not at all
for example, if they traveled in one direction, they could have travelled any number of kilometers and still have 0 distance between them 🙂
you're probably just confused because the triangle you drew makes it look like 189 is the longest side 😛
this is a task about the cosine theorem, basically.
A hint would be good enough.
8 or 9?
triangular inequality
@zinc dragon the constraint not mentioned explicitly is c < a+b
So you're claiming that the question is incomplete?
no, it's not incomplete
the constraint is just the strict triangle inequality
i'm guessing you're looking for some strategy other than brute-force counting
it follows that ||c < 10||
So c<10?
But for a, b: are there any specific constraints that fix a type of values for them?
a<=b<=c
Ohh yeah, ig i see what you're talking about hobo
Yepp💯
I think he's done (?)
Yeah I thought so I waited a couple minutes to make sure lol
I just have one doubt. So (a, b, c) cannot be (9, 1, 10) because c<a+b so if i choose (8, 1, 10), there aren't any other constraints holding the formation of a triangle, are there?
Okay got it.
how many?
I haven't calculated yet. Wait.
8
@mental vessel i am sorry for holding you. This channel is all yours
no its okay
thank you
dont mind my triangle cause its a little weird compared to the question
but i know the angle cant be 50.6 degrees its over 100, what did i do wrong?
244 is the largest side and the angle opposite to should be the largest(unlike your diagram)
I see no mistake in your solution.
in the question it says the two airplanes are 189km away from eachother, which is what i have
one airplane goes 168km and the other goes 244km
244 is the largest side and the angle opposite to should be the largest(unlike your diagram)
i.e. your diagram isn't scaled properly
Your solution is correct, it is 50.6° but diagram is incorrect
So like that then
then it asks the angle between the two flight paths, which would be opposite to 189 right
Yes
how would i find a quadratic function when given the x intercept of x= -5/8 ? yes its only one x-int
is it known that that's the only x-intercept?
or is there another one at an unknown location
and you're absolutely right.
the equation will take the form $y = a(x + \tfrac{5}{8})^2$, where $a$ is either arbitrary or to be determined by other info
Ann:
After someone’s answered the person above me’s question, could someone check my work and tell me if this is right?
@hallow crystal didn't check the entirety (looks okay though) but yes, khun
<@&286206848099549185>
what would question 2 look like compared to quesiton 1? I'm not sure how to differentiate a-b from a+b or how to show it with a compass and a line
on b?
yes because subtraction
i get it now
thx
does the dot go on the arc on (a-b)?
can you show me what a+2b-c would look like?
if you understand 1 and 2, combine the two ideas
@silent plank could you answer my question?@pliant osprey
which part of the proof don't you undertand?
you've counted the area of the big square in two ways
the line before that says
we're going to write the area of the larger square in two different ways
- is one way (using the sides of the large square)
- is the other way (using the smaller square and the 4 triangles)
those both represent the area of the larger square
and would have the same value
how come they are using the ways to equate then simplify to get the theoreom?
2 ways
i know they mean same thing
because that's the approach they're using
Given the directed line segment PR below, find the coordinates of q on pr such that the ratio of pq to qr is 2:1. P being -2,5 and R being 1,-7
whats that
to get a relation between the variables a,b and c
ok but using area to find an equation that only gives you answers to missing sides doesnt make sense
areas of all squares triangles in both ways are used then equated to simplify but the simplified equation is pythagoras thereom however, the theorem when used gives answers to mising sides
how does maths go from areas to sides?
@hallow crystal didn't check the entirety (looks okay though) but yes, khun
@pliant osprey
- gives you information about a and b (in relation to Area)
- gives you more information about a and b as well as c (in relation to Area)
and together you get a relation between those 3 variables
Given the directed line segment PR below, find the coordinates of q on pr such that the ratio of pq to qr is 2:1. P being -2,5 and R being 1,-7
i mean you agree with all the math right...
I’m sorry I love everyone’s pfps-
a^2 + b^2 = c^2
is the logical conclusion to everything set up before that
ahhh is a matter of cancelling the 2ab giving you equation to find all sides only
Is there a symbol for midpoint? Do I rlly gotta write it all out
well yeh...
how do i ask questions and get a reply quicker btw@silent plank
be explicitly clear upfront about which parts you need help with
LOL professional tutoring ❤️
ok, just asking im quite new to server 🙂
M for midpoint
@silent plank can you help me
subscripts to indicate which segment
M for midpoint
@silent plank
OHHH I was wondering why the formula has Xm and Ym instead of X1 and Y1
should be capital M
Given the directed line segment PR below, find the coordinates of q on pr such that the ratio of pq to qr is 2:1. P being -2,5 and R being 1,-7
parentheses around points, math is also case sensitive, keep labelling consistent
have you drawn a diagram?
P is (-2,5) and R is (1,-7)
i have to find q on the line pr
The ratio of pq to qr is 2:1
the change in the x and y coordinates will also be in the same ratio
Q on the line PR,
RQ to QR
How do you factor a five term polynomial
well, you can guess 3 roots and get left with a quadratic
Why do you need to, though?
my teacher doesnt really like us so hes torturing us with 5 term polynomials
i'm just tryna study for the test tmrw that this will most likely be on
rat root theorem
oh, yeah, I remember that
don't think I ever used that except for the test that was for 😅
thank you boys
Why do u have to subtract point A’s coordinates from the midpoint’s coordinates in order to find point B’s coordinates?
I know you need to subtract because the original midpoint formula is adding, but shouldn’t it be vice versa?
Shouldn’t you subtract the midpoint from Point A instead
In order to find Point B
<@&286206848099549185> :
Wut?
A(a) B(b) M($\frac{a+b}{2}$),
$b = \frac{a+b}{2}*2-a$
ThisIsMyName:
sin^2(x) cos^3(x) = cos(x) to be sure
right ?
sin(2x) can never be +/- 2 in the real domain
so only solutions for cosx = 0 count
I’m trying to “visualise” this question
I’m unsure if my depiction of it is correct
How do I find the mininum value
for question c
Im trying to find the vertical shift for my cos function
Vertical shift = Max+Min/2
Max-Min /2 was equal to = 25.4
Oh nvm
Hi!
I need help with intersection of bounding boxes
Does someone happen to know how to calculate the intersection of rotated bounding boxes?
im trying to figure out what the shared arc is
i think i can use opposite angles of quadrilateral
if i construct cb
do you know inscribed angle theorem?
i think i can use opposite angles of quadrilateral
i highly doubt you'll get anywhere with that if you don't use the inscribed angle theorem
yes
I got 150
hold up
using the opposite angles of quad and the inscribed angle theorm
yw
It's circle geometry
trigonometry is about triangles but i think it falls under geometry ( triangle geometry?)
the proofs aren't too hard to learn/ understand
just need to practice and get used to it
its just sometimes its diffficult to see how they can be applied in the question
its pretty fun tho
Yeah
like brain riddle
r proofs the thing with postulates
Sina=-5/13
How can one side of the triangle be 12 is it correct?
For 4,1
Never mind I figured it out
Hi i have a geometry question
Can someone help please?
Based on this
I have 10 questions
- What numbers are corresponding to 3?
- What two numbers are alternate interior to angle 4?
- Which two numbers are alternate exterior to 10?
- What number is vertical to 14?
- Angle 11 is alternate exterior to what number, and alternate interior to what number?
- Angle 13 is alternate exterior to what number, and alternate interior to what number?
- Angle 5 is alternate exterior to what number, and alternate interior to what number?
- Angle 1 is alternate exterior to what 2 numbers?
- Angle 8 is alternate exterior to what 2 numbers?
- Angle 3 is alternate interior to what 2 numbers?
I need help with the alternate interior and exterior angle questions
I did all of them but i still dont get it and dont know if they are right
@muted hollow can i see your answers to them in order to check if they are correct
On 1 if you think that 7 and 2 are corresponding to 3, what stops you from 6
You cant do diagonally
Its only downa nd across
Down and across*
That was my teachers answer
Wait what? I'm assuming the 4 lines are parallel right?
Just its right xd
I may have missread it
Oh ok
I mainly need help with the alternate interior and exterior
I have no idea how to do it on a 2 by 2 grid thing
I know how to do it on a 2 by 1 though
Just not a 2 by 2
2 seems correct
3 is too correct
4 as well
5 as well
6 as well
is the 7) a 1 on exterior?
Yes its a 1
Oh really?
yeah i couldn't find any mistake at all
I still dont understand fully when the number srae interior and exterior on a 2 by 2 like that
Could you explain?
wdym by 2 by 2
sure
See look
Wait
For exaplme on number 8
Example*
OH WAIT
I think i get it
Its asking angle 8 is alternate exterior to what 2 numbers
But 5 is on the interior
But 8 is the alternate to 5
And 8 is on the exterior
I think i get it
what i usually do when alternate exterior or interior angles is to like forget the other line we are not gonna use, and focus on the 2 by 1
and then change lines
to get the other one
that might be useful
Yeah i get what you mean but like
I feel like the exterior and interior changes when it gets to a 2 by 2
But it r3eally doesnt
Its confusing
Really*
practice and practice and the more problems you do the less it'll appear confusing
especially in maths
Yeah but i am just nervous that the teacher will mark them wrong as a homework assignment
the more situations you've come upon before the exam, the more experience you'll have when dealing with the test
Yeah but i am just nervous that the teacher will mark them wrong as a homework assignment
they are all correct lol
believe in yourself
is that really necessary to ask?
Im only 14 turning 15 on october 13th
nice!
around 18 is a good guess
Ah ok
for triangle abc prove that (a+-b)/c = sina =- sinb/sinc
how do i prove that
ive been at it for like an hr with nothing
Hi so I’m in geometry and me and my friend got different answers on a problem, with his being right. Can anyone explain where I went wrong/why it’s wrong?
Because they got E being 60 degrees with x being 4 and y being 10
,w 10x+3y +4y -7x +8= 90, 5x+4y = 3(4y-7x+8)
?
Oh wait it’s 7y right?
yes
Lol dumb mistake thanks for the help
And that’s it right?
@silent plank it’s just that right? From there is it all correct
Like if I change that and proceed with said changes it’s correct right
it pretty much renders everything after irrelevant
Like adjust based on first equation changes
redo the whole thing
Ok but like for the systems that’s right?
Like original 2 equations
Sorry I’m kinda tired today
So I sound really dumb lol
the other eqn looks ok
I’m sorry I sound so dumb
guys
can someone help me with something really easy
i dont know how to do it though
!r1
we won't be able to either
rule 1, don't ask if you can get help, just post it. #❓how-to-get-help
for triangle abc prove that (a+-b)/c = sina =- sinb/sinc
how do i prove that
ive been at it for like an hr with nothing
Hey, can anyone give me any tips with the following problem: You have a DIN A4 sheet of paper from which you want to make the largest possible sugar sachet. Make a suggestion on how to make such a sugar cube - also give the dimensions of the sugar cube
(a+-b)/c = sina =- sinb/sinc
something looks off about that.
no, where are you getting sqrt3/2
That side of the is sqrt3/2 and the hypotenuse is 1
that doesn't tell me how you're getting that specific value though
°, but that would be ok
But how would I isolate the variable
So sin58=24/x
where are you suddently getting cos
Oh sorry
note that my main question was specifically where the sqrt(3)/2 is coming from
In a 30/60/90 triangle isn't the leg sqrt3/2
ratio of the leg opp 60° and the hyp would be sqrt(3)/2
but in what way is this a 30°-60°-90° triangle
can someone link me a review page or packet for geometry i need to brush up
I think I need a brain
nope
check how you're setting up your trig ratio
you're saying that the ladder is touch the building at a place higher than the ladder itself
for triangle abc prove that (a+-b)/c = (sinA +-sinB)/sinC
how do i prove that
ive been at it for like an hr with nothing
@bitter jetty something looks very off about that statement
still looks off
math is case sensitive
o ic
ok
now is it gud
for triangle abc prove that (a+-b)/c = (sinA +-sinB)/sinC
can u help
@silent plank
start with the sine rule
$\frac{a}{\sin(A)} = \frac{b}{\sin(B)} = \frac{c}{\sin(C)}$
ramonov:
one question
Does it mean that the volume of a pyramid for infinity n is infinity=
using that can get you the equations: \
$\frac{a}{c} = \frac{\sin(A)}{\sin(C)} \
\frac{b}{c} = \frac{\sin(B)}{\sin(C)}$
Because I thought it would become a cone
ramonov:
yes
and then add/subtract them
how can anything have an infinity volume
yes
this for n to infinity
you'd be adding or subtracting the same value to/from each side
yea but for infinite n the volume of a pyramide is infinity isnt it
but in this formula I don't get how a changes for more n's
because a has to become shorter if we add more sides to a pyramid
i got to sinA = sin(180-B+C)
and that a/c = sinA/sinC
but im stuck again
,help
A brief description and guide on how to use me was sent to your DMs! Please use ,list to see a list of all my commands, and ,help cmd to get detailed help on a command!
sinA = sin(180-B+C)
not quite
insufficient parentheses
what's the relationship between A,B,C in a triangle
What is a discontinuity im so confused
$2y + (4x - 100) = 3y + 30 + (x + 5)$
@modern sorrel
$-3y - 6x = -420 \qquad 3y + x = 145$
LifeSource:
$-5x = -275$
LifeSource:
$5x = 275$
LifeSource:
$x = 55$
LifeSource:
$55 + 3y = 145 \implies 3y = 90 \implies y = 30$
LifeSource:
$(5y + 38) = (8x + 26) \qquad 3x + (5y + 38) = 180$
LifeSource:
Uh where's $\vec{AR}$?
TedNowKaczynski:
Could you provide the complete image?
I’m trying to find the horizontal phase shift and I attempted to do this
By plugging in my Y as 36 and x as 1
And I have the other variables and what they mean
Though I hit a dead road
Because I got “syntax error” when I try doing
-1^-sin-1 to get rid of the sin
-1^-sin-1
what.
your calculator is going "what the fuck are you trying to say" at you
that would be sin^-1(-1**)** = sin^-1(sin(pi/6 + c))
you APPLY sin^-1 to both sides
not raise it to the power of a function
oh
When I mean by
sin^-1 I meant like
I applied -1 first then sin^-1
like this
i thought that’s how we do it lol I guess I was wrong
ok now I got
2.094=C as my horizontal shift
Hello.
Is there anything wrong with this intuition: to find the angle a vector makes with a particular axis, find the dot product between the vector without that axes component, with the unit vector in that given axis.
The reason I'm asking this is since my book gives these formulas above which was not what I was thinking.
$\bar{r} \cdot \bar{i} = \lvert r \rvert \lvert i \rvert cos(\alpha)$
$cos(\alpha) = (x\bar{i}+y\bar{j}+z\bar{k})\cdot\bar{i}/\lvert r \rvert$
So the angle $\alpha = cos^{-1}(\lvert x \rvert)/\lvert r \rvert)$
livvney:
Similarly you can find the other angles
@jolly bear make the vector representation of the situation and solve accordingly
@left storm what have you attempted?
@left storm for 11, you only need to know the distance formulae, for 12 you just have to solve the linear eqns
Without solving for C using algebra, is there any ways I can find the horizontal shift
by simply looking at the graph
Im just wondering
by simply observing the sine function's picture
Wait can anyone here help check my calculations
something went off
Because Im supposed to have a horizontal shift of -2.17 according to my graphing calculator
though when I plugged in a month and temperature (the first month and temperature) to solve for C
I get -4
Moved to #help-9
it is trivial
bruh why did u take a picture of your laptop from your phone
- distributive prop, addition prop, substitution prop
- addition prop, addition prop, divison prop
shush gimma a break
LOL
what are u asking
if my answers were right
isnt that just trivial though
does a unit on a coordinate plane mean 1 box on it or like 1 of the things that the number on the sides represent because like 1 box doesn’t mean one when ur graphing but if the question says 1 unit = 1 inch are they reffering to one box on the plane or not
Can two points be collinear?
@shrewd bay what do you think
Can someone ease explain where 1600 is coming from out this equation. I'm considering my options here, I'm doing 9-1 and 9+1 which are equaling 8 and 10. But 8^2 is 64 and 10^ is 100
What should I be doing differently
They're simplifying 1 - (9/41)^2 right? And you might know 1 - (9/41)^2 = 1 - 9^2/41^2. Turn 1 into something so the expression can be written as a single fraction and you'll have answered your own question :)
@upper karma I think I might be a little slow. So 1 - 9^2/41^2 = 80/1681?
You have to write all numerators above the common denominator
I get it now!
thank you
Err 1 - 9^2/41^2 = 1600/1681 but glad it helped
Lol yeah so it's 1681-81 / 1681 = 1600 / 1681
Great
Can two points be collinear?
The definition I was giving said collinear has to be three or more points.
But isn’t collinear points on the same line?
So wouldn’t two points be on the same line?
Considering there needs to be a set of points on the same line for them to be colinear, yes, your observation would be correct
I’m not sure why the definition from my teacher says three points.
So we just talk here for geo?
@upper karma yeah, there are other things too like pre calc and pre algerbra
Yeah I saw that
oh mb
It’s alr💀
so your new here?
you're*
Yeah I joined like a little while ago
that's cool, i joined a few days ago so, im basically new too.
what grade are you in
sorry that sounded kinda creepy. im just wondering bc i wanna know what grade ur taking this class in. yk what i
mean
Lmao yeah
I’m a freshman.
oh me too
i took the algebra regents in 8th. Thats my nyc curriculum though.
That’s lit. I’m from ny too
thats crazy
anybody know the exact value of sin 16pi/3?
i found the answer is squar3/2 I just don't know why
It's -√3/2
yup that's what i ment
sine is negative in third quadrant
right
5pi is just 4pi + pi i.e 2 full rotations then a pi
Add pi/3 to it , it brings it to third quadrant
thanks
can someone please explain the reasoning behind why this is the case
if an angle is in the second quadrant.
I don't get these relationships at all
all i know is arcsin(X) + arccos(x) = pi/2
Do you want a proof of why arcsin(x)+arccos(x)=pi/2? @onyx tapir
@upper karma Yes please
Also, the reason why and how you can create a relationship between arccos( - value ) and arcsin (+ value)
@upper karma Yes I have.
apologies for taking some time to reply as i am in a class
when you can respond, i'll check it out and let you know
okay, i'll maybe go through diffentiation method then
@upper karma yes 🙂
Take your time
Yes I am
Let's start by drawing a triangle as such $\$ $\begin{tikzpicture}
\draw (-4,0) node[right=50pt, below=5pt] {b} -- (0,0);
\draw (0,0) node[above=40pt, right=5pt] {h} -- (0,3);
\draw (0,3) -- (-4,0) node[above right=50pt] {1};
\draw (0,0) -- (-0.5, 0);
\draw (-0.5,0) -- (-0.5, 0.5);
\draw (-0.5,0.5) -- (0, 0.5);
\draw (0,0.5) -- (0, 0);
\filldraw[fill=green!20!white!, draw=green!50!black] (-4,0) -- (-3.4,0) arc [start angle=0,end angle=38, radius=0.6];
\filldraw[fill=green!20!white!, draw=green!50!black] (0,3) -- (0,2.4) arc [start angle=270,end angle=218, radius=0.6];
\node at (-0.4,2.2) {$\alpha$};
\node at (-3, 0.3) {$\beta$};
\end{tikzpicture}$
$\$ Now let's do a little bit of trigonometry, $$\sin(\alpha)=\frac{b}{1}=h$$ $$\sin(\beta)=\frac{h}{1}=h$$ $$\cos(\alpha)=h$$ $$\cos(\beta)=b$$ now applying pythagoras $$b²+h²=1²$$ $$b=\sqrt{1-h²}$$ so now we will change the trig statements we did before to make all of them in terms of h. $$\sin(\alpha)=\frac{b}{1}=b=\sqrt{1-h²}$$ $$\sin(\beta)=\frac{h}{1}=h$$ $$\cos(\alpha)=h$$ $$\cos(\beta)=b=\sqrt{1-h²}$$ and now pulling out knowledge of $\sin(\alpha+\beta)$ $$\sin(\alpha+\beta)=\sin(\alpha)\cos(\beta)+\sin(\beta)\cos(\alpha)$$ and from what we got before $$\sqrt{1-h²}\sqrt{1-h²}+h²=(1-h²)+h²=1$$ hence $$\sin(\alpha+\beta)=1$$ now the final move, we know by the unit circle that $$\sin({\color{green}{\frac{π}{2}}})=1$$ $$\sin({\color{green}{\alpha+\beta}})=1$$ hence, $$\alpha+\beta=\frac{π}{2}$$ and finally by the trig rations we did at the very beginning $$\cos(\alpha)=h\implies \alpha=\arccos(h)$$ and $$\beta=\arcsin(h)$$ and subbing that back into $\alpha+\beta=\frac{π}{2}$ we get the desired proof $$\arccos(h)+\arcsin(h)=\frac{π}{2}$$ which works for either letter.
The drawing took me 90% of the time but there we go
Typo
Al𝟛dium:
Yw!
With regards to the example i sent above
why is that the case logically?
I know arccos(4/5) = pi/2 - arcsin(4/5)
From the proof you showcased
but not sure about this?
@onyx tapir i will add the reason to that to the text so that you have it all jampacked
Let's start by drawing a triangle as such $\$ $\begin{tikzpicture}
\draw (-4,0) node[right=50pt, below=5pt] {b} -- (0,0);
\draw (0,0) node[above=40pt, right=5pt] {h} -- (0,3);
\draw (0,3) -- (-4,0) node[above right=50pt] {1};
\draw (0,0) -- (-0.5, 0);
\draw (-0.5,0) -- (-0.5, 0.5);
\draw (-0.5,0.5) -- (0, 0.5);
\draw (0,0.5) -- (0, 0);
\filldraw[fill=green!20!white!, draw=green!50!black] (-4,0) -- (-3.4,0) arc [start angle=0,end angle=38, radius=0.6];
\filldraw[fill=green!20!white!, draw=green!50!black] (0,3) -- (0,2.4) arc [start angle=270,end angle=218, radius=0.6];
\node at (-0.4,2.2) {$\alpha$};
\node at (-3, 0.3) {$\beta$};
\end{tikzpicture}$
$\$ Now let's do a little bit of trigonometry, $$\sin(\alpha)=\frac{b}{1}=h$$ $$\sin(\beta)=\frac{h}{1}=h$$ $$\cos(\alpha)=h$$ $$\cos(\beta)=b$$ now applying pythagoras $$b²+h²=1²$$ $$b=\sqrt{1-h²}$$ so now we will change the trig statements we did before to make all of them in terms of h. $$\sin(\alpha)=\frac{b}{1}=b=\sqrt{1-h²}$$ $$\sin(\beta)=\frac{h}{1}=h$$ $$\cos(\alpha)=h$$ $$\cos(\beta)=b=\sqrt{1-h²}$$ and now pulling out knowledge of $\sin(\alpha+\beta)$ $$\sin(\alpha+\beta)=\sin(\alpha)\cos(\beta)+\sin(\beta)\cos(\alpha)$$ and from what we got before $$\sqrt{1-h²}\sqrt{1-h²}+h²=(1-h²)+h²=1$$ hence $$\sin(\alpha+\beta)=1$$ now the final move, we know by the unit circle that $$\sin({\color{green}{\frac{π}{2}}})=1$$ $$\sin({\color{green}{\alpha+\beta}})=1$$ hence, $$\alpha+\beta=\frac{π}{2}$$ and finally by the trig rations we did at the very beginning $$\cos(\alpha)=h\implies \alpha=\arccos(h)$$ and $$\beta=\arcsin(h)$$ and subbing that back into $\alpha+\beta=\frac{π}{2}$ we get the desired proof $$\arccos(h)+\arcsin(h)=\frac{π}{2}$$ which works for either letter.
And for your case, $$\arccos(-\frac45)=\frac{π}{2}+\arcsin(\frac45)$$ notice that arcsin is odd, which means that $f(-x)=-f(x)$, and using common sense $-(-\frac45)=\frac45$ : $$\arccos(-\frac45)=\frac{π}{2}+\arcsin(-(-\frac45))$$ using arcsin's parity $$\arccos(-\frac45)=\frac{π}{2}+(-\arcsin(-\frac45))$$ which ends up with the original identity $$\arccos(-\frac45)=\frac{π}{2}-\arcsin(-\frac45)$$ $$ \arccos(-\frac45)+\arcsin(-\frac45)=\frac{π}{2}$$
@onyx tapir does all this clarify it?
That makes so much sense
Thank you so much for your time
You said notice that sin (4/5) is odd
What does that mean?
You said notice that sin (4/5) is odd
i did not say such, i said arcsin was odd
does anyone know how to do sqrt(-2) *sqrt(-2)?
Uh you're looking for $(\sqrt{-2})^2=(i\sqrt{2})^2=2i^2=-2$
TedNowKaczynski:
by definition of the square root, sqrt(x)*sqrt(x) = x
Uh isn't that how you define i though?
sqrt(-1) is defined to be i
So sqrt(-2) is just sqrt(2)i
you should have put i in front of the root
Umm it doesn't seem clear? I'll change it then.
it looks like i is still in the root
it looks like i is still in the root
if you dont look closely
TedNowKaczynski:
Aight then
ok ty bros does (sqrt-4)^3 equal to -8i or just 8i?
-8i
Square root and the square takes out eachother
No need to convert to imaginary figures
Nope but if you take the third root instead it will take out ^3 and leave you with - 4 🙂
TedNowKaczynski:
@somber coyote I meant this one when I made my statement before
it is trivial
Well maths is about to be as efficient as possible while sparing as much time as possible
How would I calculate the area of a spherical square?
so it's like 2 equal triangles, one angle is 2 times larger than other 2, and 2 sides are known
is that right?
apply properties of straight lines to set up some equations
what shld my equations be
8x=2x+4y?
or
4x+7y+2x+4y=180
idk i hvavent done this in ages
both
oh
help what do I do
What is like of symmetry?
and what are angles
I know one is E, but what do angles mean
lol why are they using integers to denote a variable
that is silly
but yea just form an equation and then u can solve it
rip do u know what an angle is lol
I’m in geometry and my friend who Idk what class she’s in asked me to help her with this problem 😭 I don’t think we’ve done this unit yet in my class
rip do u know what an angle is lol
@paper vale
Did I get the 180° part right at least 😔
<@&286206848099549185>
i cannot figure this out
is this a test
no it’s a warmup
uh ok
what have you tried
if that counts as a test idk
does it count as grade?
the warmup
like 5 points but only as participation
ig that's kind of in the limit of okay
what have you tried
@upper karma ...?
ABC and CDE are two equilateral triangles. The two triangles have A as a common corner, see the figure below. Prove that AD=BE
Hint: compare triangles ADC and BEC with each other
@pliant dawn
since it is equilateral, then each angle inside the triangle equals to 60°;
as they are equilateral, their sides follow a proportion. Then, it's a product between AC and a constant (k > 1, since CD > AC);
the angle opposite to AD is a + 60° and the angle opposite to BE is a+60°. By proportion (as you see in the image), they are the same triangle and BE = AD, as desired
maybe i jumped some steps, but you can do it by yourself just seeing the image
it it trivial by spiral similarity
https://www.geogebra.org/calculator/jftndxxz
I have a problem regarding a circle and two points:
If I know:
The coordinates of point B (2,0)
The length of AB = square root of 8
A and B are both on the same circle
The radius and middlepoint of that circle is 4
How would I calculate point A?
I figured you would probably have to use the distance formula between two points:
and I know that point A would have to meet x^2 + y^2 = 4.
But from that point I got stuck
(Disclaimer: This isn't for a test or anything. It's for an animation controller program I'm writing)
Is that a minus sign?
√-9
?
@pastel anchor
yea
You can't do the square root of a negative number without using complex number
it becomes 3i
also this is #geometry-and-trigonometry , you might find more people that can answer that question in #prealg-and-algebra
im learning complex numbers in trig
ooh shit
so are there steps?
yea thats what i meant





