#geometry-and-trigonometry
1 messages Β· Page 55 of 1
well if you meant reciprocal then you have to say reciprocal lmao.
sec(x) = 1/cos(x)
but you cannot just drop the "1/..."
Still yet to understand Maths English, My teacher told me it's a whole different playing field π€¦ββοΈ
try using properties of triangles
"maths english" no this is just "basic communication"
say exactly what you mean and mean exactly what you say
are A B and C angles of a triangle? it wasnt mentioned anywhere-
So...
there's nothing particularly deep to explain, it's just plugging into the definitions of your trig ratios
huh lemme see
this question is from "properties of triangles" topic
oh a, b and c are sides of a triangle
π shoulda said so- yea so the problem is solved now if i consider it as an angles of a triangle
and A is the angle opposite to side with length a
and B is the angle opposite to side with length b
iseee
why tf do they make these questions ambiguous
tbh they gave us enough context imagine if they had to write everything there book would like a billion pages
I realised this after looking at the solution
they're just lazy π
alr
How?
what's your issue here
idk anything about it
apply difference of squares to num and denom separately, and you will get some tan(a+b) simplifications afterward.
Hi everyone, I would like to ask about one type of problem associated with power of the point, when you can rotate chord in circle and get another 4 points that lie on one circle. For example, I have problem like this: given a parallelogram with configurations as in the picture and you need to proof that 4 points (2 vertices of the parallelogram, the bases of the perpendicular and the continuation of the median) lie on one circle. So, does anyone know problems with a similar idea?
yea I cannot open the file
Yall might have just downloaded malware-
i did not download it
i saw that it is a file with no extension, and for this reason alone i raised the suspicion
Sorry, give me a second
Nice
(I removed one of the copies)
How do i find the maximum and minimum in problems like this one generally?
The official solution is just hit and trial
But there gotta be a better way
And like how would i do it if i had to find the minimum instead of just its sign?
you can convert it into a geometry problem
Is it postive
Not in his syllabus
?
sure but why would that help
its negative
are u familiar with inverse trigonometry
also the angles can be negative
not jee level but enough yea
well you can just prove that it is negative at some point, then you've proved that the minimum must be negative (since the minimum must exist as the expression is lower bounded by -3)
yea but that was more hit and trial
(for min the book did -pi/2, -pi/2 and 2 pi but why)
oh wait it doesn't
thats 0
hmmm
Least possible value (-1) yeilds at -Ο/2
this was in amit m agarwal
Really good book
like sure but is there some way to defintely prove that this is the most optimal combination
I just have the calculus one
yes the calc one is jod, trig one on the other hand is just pain
With Domain range I think
can we?
like sure the sign determination is ez
Ye
Lemme see it
:D thanks
nope
cuz alpha beta gamma dont have to fit the range of sin inverse
it would be one of the infinite possible values of A right?
ye so thats why we cant use it in this problem ig
Restricted range
Domain expansion
jjk
Else if u don't consider that there could be infinite values of a b c
Boxing ring
yea but we just care about the case of a b c when the resulting value is minimum
Resulting value of sina + sinb+ sinc
yea
sure we could write c = pi - b- a and get an eq in 2 variables but i dont see what i can do further
not gonna work
hmmm
this shit is so confusing
sin(a+b) is sinAcosB + cosASinB
Sin C + Sin D is 2SIN(C+D/2)*cos(C-D/2)
remembering the formulas is like easiest part of trig, applying them is smthn else though
i hate manipulations
fr
broo fr
try this if you havent tan(6)*tan(66)*tan(78)*tan(42)
like how am i supposed to think of that in an exam setting
yea π like how tf am i gonna think of that in an exam setting
our tchr gave that one to us in the class none of us solved it
what grade
tan(a) tan(60-a) tan(60+a) = tan(3a)
yea
11th
im in 9th π
like trig can be fun but dont ask shit like that in an exam bruh-
th- @proven summit see this-
i learnt trig when i was in class 8
like
identities
and all that
i forgot most of it
ahem lmaoooo nice, icse kid i assume?
bro tf lmao have fun
10th grade lvl?
things that includes triangles
hmmmm solutions of triangles can be brutal sure
you will get thru it though you have plenty of time
im only able to deal with questions including sin cos and stuff
when i get question with finding the length of the triangle
idk what to do
uh get some book read some illustrations then practice
true
where can i use actual calculus?
@proven summit dont you ever dare pick on me again-
uh like have you done graphs?
and like proper coordinate geometry
what?
no
ignore that π
who cares abt graphs
then you cant use calculus
main use of calculus is to extract information from graphs
areas tangents and stuff like that
like in physics too you are basically finding the area when you are integrating a function
thats what integration fundamentally means
to find the area under the graph
π lmaoo thats why you dont just mug up formulae
i dont either but calc is fun
ive mugged it all up
sure you probably might not know the significance of what you are doing
in trigonometry
how tf am i supposed to know that i multiply the equation by fucking 3/2*2/3 to get the answer
but just the feeling of successfully solving an integral or a limit you spent hours on is satisfying
honestly get a tchr they would explain it much better than i can
its embarassing π
no? thats where you are wrong
there are so many integrals you just cant solve in less than like 10 mins at least even if you know the idea behind them
i cant solve integrals which includes more than 2 terms
wdym by 2 terms?
like you couldnt solve sin^3(x) cos^2(x) sec^2(x)cosec^3(x)?
dont rush.
Nope
maybe cosectan
sinx?
nope
(sin x)' = cos x
yes
yea
i remembered those two
cause i used them in differentiation
basic
idk others π
why is derivative of sin(x) equal to cos(x)
never used
?
Depends on what definition of sin x you're using
idk it just does
It follows pretty nicely from the series definition
maybe graph
i am not asking as in for me, just asking so that he gets his concepts straightened out
nope
sin/cos = tan
learn, dont mug up
π lmaoooooo
the complex number definition is prettier if you ask me
(but for him i was expecting him to use the basic limit defniition of derivative)
i dont know limits
ahhhh
and you know integrals, nice
lim x => 0
You definitely need to go over that again
i forgot
you are moving too fast-
sure i get the feeling of wanting to be the best
im in a valorant game
lmfao
wdym slow down
slow down as in dont go so fast that you complete entire calc in a week then next week you know nothing
you are fucked up beyond repair then-
127.0.0.1
1.618.69.420
what will i do with localhost-
missile strike initiated
def not calc
inter continental ballistic missile
wait i need water
idk i skipped all of calc and geo
number theory nd pnc are the simplest topics for olympiad math
but yea your choice
anyways you aint clearing ioqm by mugging up shit anyways
on two fucking lines
i can
i can solve some ioqm pyqs
us fr lmao like i can tolerate schl geometry but ioqm geometry fucking killed me
whtg grde are u
if i score 2 without any preps?
score 10 then we'll talk if you score 10 at home youd prolly get like a 5 there cuz of the stress
i was scoring in 20s in mocks
but in the real exam i got 15
so yea
in 11th?
9th
mmm
the math enthusiast in me wont let me tell that to someone who think maths can be done by mugging up-
i was kidding
i dont mug
π like i believe you?
i know from where sin(a+b) came
doesnt matter :>
sin(a+b) proof is weird enough anyways lmao
yeah confusing
yea i dont- slow down
pls tell
ok
(2022 cuz i was in 9th when i gave it)
i onkly find paper with answers
uh dont cheat ig?
if you cheat then whats the point
you need questions?
you will find some here
yeah
What
that kid is doing calc in 9th grade- im still in 11th
i mean its not that hard
but also i wouldnt know if i would consider knowing how to solve basic integrals without knowing what limits are "doing calc"
i mean i guess technically
xD
its not ik π but he was picking on me for liking it soo yea
π lmaooooo fr
when did he do that πΏ
a lot of times in #calculus
If you spent as much time helping others as hanging around in discussy
You could be green by now
i dont even hang around in discussion that much π- i have like less than a 100 msgs there im sure
(also im dumb enough cant help others-)
and dont have enough patience to solve the easier problems
i help ppl in calc tho sometimes
Is the domain of the equation $\frac{\sin\theta}{1+\cos\theta}$ $\mathbb{R}-{2n\pi\pm\pi}$?
KingDanger
that +- is redundant you could just use 2npi + pi
also yea
(hence why i said rare wolfram l)
Ok
If you don't mind problems with geometric overtones, then I can suggest proving that the perimeter of an orthotriangle is 2Rsinasinbsinc, where R is the radius of the circumscribed circle of the original triangle and a,b,c-angles.
pa = ae, and ae = ba
is it just a bad picture?
yea
it says "regular" pentagon, doesnt that mean the angles/sides supposed to be
yeh
β οΈ
i mean it usually says the figures arent gonna be to scale
lmaoooo my drawing would be worse
there is no way i could draw a straight line
how did you got that
oh yeah mb

equilateral triangle given
and regular pentagon
also given
ae = ba because they the side of the pentagon
and all sides are same
even though they cant draw
(you really need to work on your definitions before attempting amc)
ae=ba???????
regular pentagon means all sides of the pentagon are equal
ae and ba are sides of the pentagon
screaming crying
Is someone able to help w using the period, for evaluation?
Cause all of these examples are confusing me tbh π
for any number x, sin(x + 2Ο) = sin(x)
Similarly for any number x, cos(x + 2Ο) = cos(x)
So for example, letβs say you want to figure out sin(9Ο/4). Then this is an example where this rule is useful. To see why, we know 9Ο/4 = Ο/4 + 2Ο. Thus, sin(9Ο/4) = sin(Ο/4 + 2Ο) = sin(Ο/4) = sqrt(2)/2
does what I said above make sense?
Ohhhh i see mow
Now*
Because 9pi/4 is jus equivalent to pi/4
Since you do a whole revolution and then a pi/4 of a revolution
Right?
yeah, so the problems you probably encountered before these ones were evaluating sine and cosine at angles between 0 and 2Ο
But these rules allow you to deal with angles outside of that range, so you can evaluate sine and cosine of angles less than 0 (say sin(-Ο/3)) and sine and cosine of angles greater than 2Ο (say sin(17Ο/4))
So say you want to find sin(17Ο/4)
As you said, you basically just do a whole revolution of 2Ο, and the sine value will remain the same
So putting this rule in action, we have sin(17Ο/4), but the angle is too big, so letβs move 2Ο backwards - - so we see this is the same as sin(9Ο/4) - - still too big, so we move 2Ο backwards again - - this is the same as sin(Ο/4), and since Ο/4 falls within the range of 0 and 2Ο (and itβs one of the nice angles on the unit circle), we surely can evaluate it
doesnt look like a regular pentagon lol
?
If you add all the angles of a pentagon, itβs 540Β° .two of them are ninety. If you subtract them itβs 360Β°. There is a triangle at the bottom. Use the sine or cosine theorem. Itβll find the angle degree
Thatβs what I think
This problem is giving me a lot of trouble, Iβve tried messing around with it but canβt find anything
did u manage to solve it?
once u extend the perpendicular line like so
you can solve it pretty easily
I didnβt
what can you say about angle PYH?
Itβs a right angle?
PYH? check again
this angle here
angle PYH
thats how angles are named, with 3 points, the vertex of the angle is the middle letter
so for example in the diagram they give u that angle ZWV = ZWP = PWZ = VPW = 140 degrees
a thing about angles is that if u have an X of angles
opposite angles will be the same
yes
I didnβt see that there
ok so now
we know PYV is 3x
and PYH is x
so HYV is?
140-4x?
not quite
check what angle im talking about again
yes
we can express HYV in another way
and that allows us to solve for x
do u think u can try to find it?
The sum of the angles of a triangle being 180 degrees
I was gonna do something with the triangle HVY
cool idea but u dont need that here if u dont wanna use that
u can do it solely within the parallelogram
we're given that angle ZWV is 140 degrees
and also that angle ZYH is 90 degrees
try to use that in order to express HYV in another way
25?
yes π
they become easy as you gain intuition and practice
and im sure u will gain that intuition
fast
lmao
Nahhhh
nah trust
ur actually a genius
i think ull find geometry pretty fun
Iβm not escpecially smart I donβt think
ur pretty smart
Nahhhh
how do I find the reference angle of cot(180)?
okay and what about the exact function value?
its undefined
notice that cotangent is given by cosine/sine
and cosine 180 degrees is -1
sine 180 degrees is 0
so cotangent 180 degrees is -1/0
ur dividing by zero here which isnt allowed
okay, draw the reference angle and find the exact function value if it exists of Sec(-270)?
If sina= 5/13 and sinB= 12/13, where a and B are between 0 and Ο/2, evaluate sin(a-B) and cos(a+B).
i tried proving it, this is my proof:
-
let:
A, B, C be points on a sphere with center O and radius OA = OB = OC = 1 -
draw:
CA' and CB' to be tangents of the sphere at C in direction of A and B respectively
then A'CO and B'CO = 90 deg. -
draw:
extend OA and OB until they intersect CA' and CB' respectively.
call the intersection points A' and B' respectively. -
denote:
A = CAB B = ABC C = BCA
a = BOC b = AOC c = AOB
a' = CB' b' = CA' c' = A'B' -
planar law of cosines on triangle A'CB' gives:
c'Β² = a'Β² + b'Β² - 2a'b'cos(C) [1] -
from definition of tan(x), and since A'CO = B'CO = 90, and OC = 1:
a' = tan(a) [2]
b' = tan(b) [2] -
[1] and [2] together make:
c'Β² = tanΒ²(a) + tanΒ²(b) - 2tan(a)tan(b)cos(C) [3] -
pythagorean theorem on triangles A'OC and B'OC along with [2] give:
A'OΒ² = 1 + tanΒ²(b)
B'OΒ² = 1 + tanΒ²(a) -
apply the trig identity 1 + tanΒ²(x) = secΒ²(x):
A'OΒ² = secΒ²(b) [4]
B'OΒ² = secΒ²(a) [4] -
square root both sides:
B'O = sec(a) [5]
A'O = sec(b) [5] -
planar law of cosines on triangle A'OB' along with [4] and [5] gives:
c'Β² = secΒ²(a) + secΒ²(b) - 2sec(a)sec(b)cos(c) [6] -
equate [3] and [6]:
tanΒ²(a) + tanΒ²(b) - 2tan(a)tan(b)cos(C) = secΒ²(a) + secΒ²(b) - 2sec(a)sec(b)cos(c)
cos(c) = tanΒ²(a) + tanΒ²(b) - 2tan(a)tan(b)cos(C) - secΒ²(a) - secΒ²(b) / -2sec(a)sec(b) [7] -
apply the trig identity tanΒ²(x) - secΒ²(x) = -1 and obtain:
cos(c) = -1 - 1 - 2tan(a)tan(b)cos(C) / -2sec(a)sec(b)
= 2 + 2tan(a)tan(b)cos(C) / 2sec(a)sec(b)
= 1 + tan(a)tan(b)cos(C) / sec(a)sec(b)
= 1/sec(a)sec(b) + tan(a)tan(b)cos(C) / sec(a)sec(b) -
apply trig identities 1/sec(x) = cos(x) and tan(x) = sin(x)/cos(x) and obtain:
cos(c) = cos(a)cos(b) + sin(a)sin(b)cos(C) [8] -
[8] is the spherical law of cosines. QED.
wasnt actually too difficult, only took like 10 minutes
it was quite fun seeing it all come together
esp cuz it was much much shorter than what i had imagined it to be
The proof can be easyy if you know that alternate angles are equal
I know
This definitely much simpler than the proof on wikipedia
Or maybe its just less formal idk but yea
well /shrug
it works
XD yeaa
Tips on proving trig identites? I jus started learning trig, and im stuck on ways to figure out how to prove the identites
pick some side, use known identities and algebra until it matches the other side
In most scenarios is it typically jus proving, by changing on identity?
Just play around with it until it eventually works out
The solution said the area around the corners will bein the form of sector of a circle with radius 3 and central angle 120 degrees
But why do they assume that central angle is gonna be 120? Why not smthn else like 90 or smthn
Have you drawn a diagram?
The immediate surrounding of each vertex of the original triangle spits into:
60Β° - the original triangle
90Β° - one of the rectangular parts of the desired area
90Β° - another rectangular part of the desired area
the rest - circular sector of the desired area
Sure but like how am i gonna be sure its a rectangle i mean yea it looks like one but it might end up being a trapezium for all i know
We agree that all points in this particular rectangle and sector are in the shape you're looking for, right?
Yea
And obviously the radius as well as the width of the rectangle both have to be 3.
Yep thats true
So the point where the the straight part of the outer perimeter turns into a circular arc is both on the distance-3 parallel, and exactly 3 units from the vertex of the triangle.
(It would really help to have a diagram to refer to here).
This is the diagram from the official solution
Oh i get it now, thank youu!
Are there any special properties for golden shapes apart from the long side divide short side is golden ratio? For example in 30,60,90 degree triangles the hypotenuse is double the length of the shorter side
"Golden" is not really a technical term in and of itself.
do u need help?
@deft sail draw a line from the bottom right angle to the side with length 5 which is perpendicular to that side
I just need to know how to solve it
are you aware of the law of cosine?
Sine
Compile Error! Click the
reaction for more information.
(You may edit your message to recompile.)
I keep getting the wrong answer some how
yea, so can you identify what sides should we call, a, b and c for this case
Ow
Everyone makes mistakes
@deft sail u dont need law of cosines
what are you getting?
Huh?
idk what law of cosines is but i figured it out
but the question specifically asked him to use it
Wait
sry
How do I find out without it?
so
if u draw a line from the bottom right angle to the side with lenght 5
which is perpendicular to that lenghth 5
Can you show me. Iβm confused?
Ur saying to split the triangle
(this is getting so close to the proof of the law of cosine btw if u use variable instead of values you just end up proving the law)
I see it
idk even know what cosine law is
it is exactly what you did rn
oh ok
except it has been generalised
so we can just use it as a formula
congrats for figuring out the proof on your own!
thanks
yea
The 5 will be split up evenly.
noo, use the value of cos(60) to figure out how 5 will be split
Hmmm
The line Iβm making I got 3sqrt(5)
C is sqrt(78)?
Nvm
Hereβs anotherβ¦
just use the formula
hello their
!nosols
As a helper, please do not give out answers that could be copied as a homework solution. Have the student work through the problem themselves and guide them along the way.
but also that's overcomplicated lol
why?
oh wait lol i thought A = area
use the strategy here
Lol
thanks
How to prove the 4th question.
I have got ```latex
$\cos^{6}\theta+\sin^{6}\theta=1-\sin^{2}\theta\cos^{2}\theta$ and
$\frac{4-3(m^{2}-1)^{2}}{4}=1-3\sin^{2}\theta\cos^{2}\theta$(when substituting $m=\sin\theta+\cos\theta$)
KingDanger
I am confused what to do next
Upto this step am I correct?
Anyone help me
<@&286206848099549185>
And also i got $-\sqrt{2} \le m \le \sqrt{2}$
KingDanger
square the original equation
the first eqn is wrong i think shouldnt it be 1-3 sin^2 cos^2
Please do not advertise your help channel or thread in other parts of the server. There are many people who need help, so advertising can quickly turn into spam.
that was fast
did yall check who was it?
i definitely need to start looking at names before clicking at a link-
Which equation?
sin^6 + cos^6 thing
It's 1-sin^2cos^2
uh no it should be 1-3 sin^2 cos^2
@faint pasture How could you please explain?
well sin^6 + cos^6 = (sin^2 + cos^2)(sin^4+cos^4-sin^2cos^2) we agree on this ?
yea it will be much faster that way-
you used the identity wrong in the second step
this should be a minus
Oh yes
Mb
Then it will equal
It's proven without the condition m^2 <= 2
@faint pasture Is the condition no need?
How come the SinΒ²x turned to a CosΒ²x?
do you know the identity
sinΒ²x + cosΒ²x = 1?
It's an identity
yep
Yeah?
Thank you so much
But ion see the identity on here
Gone!!! π
it's not sin^2(x) that became cos^2(x)
it's 1 - sin^2(x) that became cos^2(x)
try drawing a horizontal line that cuts the diagram in half
Wait im actually so dumb, I thought you meant the equation in the problem, not the identity itself ππ
So basically you're able to change the identity to make it equal another identity?
I said that so badly but idk how to explain it ππ
@hoary totem Are lines from the centre joining the tangent equal?
yes
... by the SAS theorem on the horizontal line, the two-ticks lines, and the 20Β° angles the 40Β° angle gets bisected into.
Angles CAO and BAO both have a sine of (radius)/|AO|, so they are equal.
Therefore AHO is congruent to AFO by the SAS theorem.
In particular HO = FO.
(Even if we didn't know that AH=AF, we'd still get the same x, but it would need more work).
(Hmm, not that much more work, in fact).
draw a diagram and work out the algebra
or i guess that would be the procedure for proving formulae not identites
oops
HOM = HOC and FOM = FOB
So what's the actual approach to my problem?
I've shown you two different ones now.
try splitting the sinβ·ΞΈ into more manageable things
That the wrong q
Correct one in help
Is it sin 70 + sin 70 in the numerator?
Or sine to the power of 7?
its sin(7ΞΈ) + sinβ·(ΞΈ)
I need someone to help me and explain to me how to solve my trigonometry homework
okay
What is SinB? I figured it was just B1
Hint: law of sines
oh wait
i see you gave the βmeasure of angle Bβ
they just want sine of the angle
Oh I see... I was meant to give the radian not the degree :/
I think my brain is fried, I for a minute thought that was the radian conversion 
What am I looking at here?
The q was wrong it's sin7β +sin3β /cos7β +cos3β
how do i solve this
A shark fin I believe β€οΈ
Yes... although I think seeing this IRL while swimming would be less insanity inducing than math 
one way is to construct AB and CD
One way to do it is to draw triangles AB and CD (like hockey said), then use the inscribed angle theorem, for example, mBDC = 1/2(161Β°). Then you can find m(DEC) (why?). Iβll leave out the rest
._.
what?
im stupid and forgot my notes whats the inscribed angle theorem
ooooooooh
not stupid for not memorizing a theorem
so why is E the center? does it look like it is
e isn't the center its the point where line BD and line AD intersect
yeah so whatβs wrong then? The inscribed angle theorem doesnβt talk about the 93 degree angle
what is the measure of angle BAC
is it 93?
why?
because of coresponding angles?
look at my diagram
oh
corresponding angles? which sides are parallel
87
why?
if things dont even look parallel and u have a good diagram and u have no reason for justifying it then those things very likely arenβt parallel
anyway, what is angle BAC?
i can't figure it out
whatβs the theorem we just talked about?
inscribed angle theorem
so β¦
80.5.....
now what is angle ABD
12.5?
yes no problem
one more thing though @crimson thunder
what is the average of arc AD and arc BC (minor arcs) in terms of their measures
whatβs their average?
less than 180?
im stupid idk
do u know what the average means in this case?
no
the sum of the numbers divided by the number of numbers
so wouldn't be 90?
e.g. the average of 1, 4, 10 is (1 + 4 + 10)/3 = 5
whatβs 25 + 161
186
no
180?
93
93? have u seen that before?
so our problem (with 93Β° angle and 161Β° arc) is just like this one, the difference is instead of given two arcs and we need to find the angle, we are given one angle and one arc and we need to find the other arc
that sounds complicated and my brain isn't processing it
it turns out whenever u have intersecting chords like this the angle between the chords is the average of the two arcs it subtends (the other arc is separated by a (congruent) vertical angle)
i understand how to solve it more simply
wdym?
isn't 93 = 1/2(161 + x)
thatβs exactly it
yes but why?
so multiply 2 on both sides and then you subtract 161 from both sides to get 25...
and this is what this is saying
oh
but where does that come from
where does what come from
do u understand how to derive it?
so then u shouldnβt be using it
i understand how to solve it
and it came from my notes that i forgot to bring home with me.....
if u donβt understand the formula but know how to solve it the way I showed or a similar way, thatβs much better
itβs not great if u donβt know how to derive it
now i know that the angle comes from the average of the 2 arcs (big one - little one / 2)
so thank you
thatβs not the point
._.
it solves it faster but if u had a harder problem where u WERENT given the formula before and it was on an exam, what would u do?
and no, it would not be trivialized by a formula like this
sorry if I sound like this but it is actually very very helpful to understand how to prove things urself
I used to not understand this but for harder problems/some actual problem solving u rlly need this
i memorize the formula and use the info given to me and taught to me to solve the problem which may include using an answer from another formula and putting into another formula
uh oh
what?
i did something wrong if you said that's not good ._.
I donβt think u do but the problem is if u come across a harder problem that canβt be solved with one of ur formulas, what can u do?
the solution I showed (which problem isnβt the best one) only relies on basic techniques, not rlly any specific formulas
(yes the inscribed angle, but thatβs like the most basic theorem relating to angles in circles)
so i do basic stuff
quick question; my geometry project is asking to list a sample space for probailities of a name spinner. Do i have to list off of the possible 276 outcomes or just 20 random outcomes
Do yk how this person got cos^2/cos^2
It appears because 1 - sin^2 (ΞΈ) = cos^2 (ΞΈ), because of the trig identity sin^2 (ΞΈ) + cos^2 (ΞΈ) = 1
it seems it might just be scratch work idk
yeah
Bruuvv
How did I not notice that ππ
Thank you ππ
For the Pythagorean identites, does it have to be in the order its said to be?
So can this equal to 1?
the Pythagorean identity is βsin^2 (ΞΈ) + cos^2 (ΞΈ) = 1β, and we know this is true; any simple algebraic manipulation will also result in an identity that is true, so what I mean is βsin^2 (ΞΈ) = 1 - cos^2 (ΞΈ)β is also an identity and so is βcos^2 (ΞΈ) = 1 - sin^2 (ΞΈ)β;
As for βcos^2 (ΞΈ) - sin^2 (ΞΈ) = 1β, this isnβt an identity (because both sides are not identical!)
We only have the first three βPythagorean identitiesβ I mentioned which have sin^2 and cos^2 in them
so yeah itβs just first three
yes
In fact, βcos^2 (ΞΈ) - sin^2 (ΞΈ) = 1β is not an identity, but βcos^2 (ΞΈ) - sin^2 (ΞΈ) = 1 - 2sin^2 (ΞΈ) is an identity; you get this from subtracting β2sin^2 (ΞΈ)β on both sides of βsin^2 (ΞΈ) + cos^2 (ΞΈ) = 1β
Oh wrd, yk what problem I'm doing?
no I donβt
Oh
Cause that's littrially the next problem that I'm doing rn ππ
Which im actually confused
πππππππππ
I'm confused tho, cause im not sure how to use identites w powers
And when a sin is being multiplied by 2
Or jus any number being multiplies by a trig function
alright, well I already gave you a big hint, although itβs not the solution: (the identity comes from subtracting β2sin^2 (ΞΈ)β on both sides of βsin^2 (ΞΈ) + cos^2 (ΞΈ) = 1β)
To establish that theyβre identical, you would ideally want to establish a chain of equalities showing cos^2 (ΞΈ) - sin^2 (ΞΈ) = β¦ = β¦ = β¦ = 1 - 2sin^2 (ΞΈ)
so since we know sin^2 (ΞΈ) + cos^2 (ΞΈ) = 1 is an identity, the equation would remain an identity if we subtracted 2sin^2 (ΞΈ) on both sides
because itβs still identically true
Oh wait you meant the pytagorean identity
I thought you meant the problem itself π
oh
Ohhh wait
I see what you mean now
Bruv when it involves the pytagorean identites, it always confuses me π
thatβs on the right track; however ideally, I think what they are looking for is this:
cos^2 (ΞΈ) - sin^2 (ΞΈ)
= (1 - sin^2 (ΞΈ)) - sin^2 (ΞΈ)
= 1 - 2sin^2 (ΞΈ)
Since itβs a chain of equalities showing that they are equal; this is because in the beginning of your work, it looks like youβre assuming they are equal to start, which is what weβre trying to prove
it takes time; eventually youβll have no problem recognizing the pyth identity (with practice)
And on the left too, cause we're proving it, no?
I hope bro ππ
I jus started learning Trig, so it's kinda confusing ππ
basically if you removed everything on the right hand side of what you have written, you would have exactly what I wrote
you can think of it like we are taking what you wrote, and only modifying one side of the equation so that the left hand side turns into exactly what is on the right hand side
@cunning lion hey i hope im not bothering u but i still dont know what u meant by this? im pretty sure i got the answer anyway but how is the highest/lowest the same as to get exactly the number #help-24 message
the biggest x for x <= 92 is 92
<= is greater than or equal to btw
idk how to write
so for the 2nd one the lowest x would be x<=84 or something???
did u mean less or greater for this
oops XD
i meant less yea
uh
its hard to swap chats XD
i dont think the 2nd one is set up correctly
there should be 5 test scores in total
oh wait
unless x was both the tests lol
oh alr
but apparently the x might not be the same so i have to do something else not 2x
n find them seperately?
i mean i think you have to minimize their sum
wdym
x+y is the lowest total score right
yea
how is x+y 164?
oh wait
nvm read that wrong
hows it great than or equal to 164
you solve 2x = 164 right
but its not actually equals
its an inequality
and its not actually technically 2x
(even tho it can be)
but its x + y
and your variables have to be greater than or equal to 164, but they also have to be the minimum that they can be
so i did 256+x+y>=420 then subtracted 256 on both sides so now i just have x+y>=164
so then id just divide that by 2 to get the final two scores as 82 (but the total score is just 164 anyway)
yeah
i mean the two final scores could be anything that sums up to 164, technically
but yeh
can anyone help
im tryna find measurement z, arc wz, measurment w, and arc wx.
ik how to find the angles but not the arcs
oh so we arent necessarily finding x or y
measure of angle z? wdym measurement z
nah, you cant
yeah
u know cyclic quadrilaterals right?
you can only find the sum
integrated quads?
so im interpreting this as like if its asking for the highest/lowest number of an average, whatever x or y is has to be result to the said average cuz u cant rlly get any higher or lower than what is asked (respectively)?
sorry im not that great with explaining math either
maybe ill find the answer one day
...sure...?
i'm not sure what you said XD
so like for example question 3 asks for the highest score she can get for the fourth round to have an average of 92,, x is 86 because it results to exactly 92
it cant be 85 cuz thats not the highest but not 87 either cuz its a little more than 92?? idk what im even saying at this point lol
or in question 4, x+y has to be 164 cuz anyything else wouldnt be the lowest or itd be too low (like beyond the B grade)
idk but u helped me get the answers anyway so thank you
π«‘
@vast skiff
!status
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
can angle Ο inbetween two diagonals of a paralellogram be 90Β°
without it being a rhombus
for instance if angles in a paralellogram are 60Β° and 120Β°
wouldnt the diagonal split them into 30Β° and 60Β° and you would get 4 congurent triangles
each with angles 30 60 and 180 - 90 which is 90
but is that possible for a parallelogram, for example sides 4 and 9
no
thats what i thought
but don't diagonals split the angles into two congurent angles
ΞΈ/2
unless i had a brainfart
give names to all relevant points, for a start
do you know if it passes through half of the first square
Okay, i understand it
if not you have similar triangles
Do you mean this line?
I got you now
Seemingly, it's not safe to assume so
use similarity of triangles
10 + x / x = 10 / β(10^2 - x^2)
$10 + x / x = 10 / sqrt(10^2 - x^2)$
ok idk how to use
$\frac{10 + x}{x} = \frac{10}{\sqrt{10^2 - x^2}}$
leon
@formal geyser
Hello everyone just now joined in this server. need trigonometry formulas from basics
this line goes hard
i rapped it in my head
??
it's a very big stretch of a rhyme
in rap you can always stretch things
you can even rhyme "ryan" with "entitled" if you say it well enough
if you mispronounce them badly enough π
what is the best visualization for math?
Sorry, i dont understand it
Did you mean AC/BC = DC/DB?
i found a plausible answer, but the work I had was awkward, since I ended up having to βsolveβ a quartic equation (which I just used a calculator to obtain the solution)
yes
But why?
if you call another side length βyβ you can obtain a system of equations then solve for x and y (but it became strange as it became unreasonable to do so without an electronic device)
Sorry for such a big f
But
I mean it is more reasonable to say that AC/BC = FC/DC
yes thatβs true
the reason is because BD is parallel to AF
wait
actually I thought you said βAC/BC = FC/DCβ
sorry
can you?
maybe
but its just simpler to go with similarity
similar triangles
it is simpler if you do it with βAC/BC = FC/DCβ
you still obtain a quartic equation, but yeah I got the same answer either way
OH WAIT NO
i meant FC
@formal geyser
$\frac{10 + x}{x} = \frac{\sqrt{(10+x)^2 + 10^2}}{10}$
leon