#geometry-and-trigonometry
1 messages · Page 379 of 1
why cant i just use the negative angle?
you can
it'll be offset by 2pi from their solution
but if you're solving an equation of the form cos(x)=c that doesn't matter
ohh ive been so confused because when i graphed it one of the awnsers was correct but the (negative) angle one was off by alot
I'll translate this
In an ABCD romb, the diagonal AC = 12, the AB side is equals to 3 square roots out of 5. Find the tangent of the angle BAC
Is this the correct solution?
@terse breach is it ok if i respond in russian?
yes
что это у тебя вообще за расчеты?
откуда взялись числа 45 и 36?
и откуда взялось, что 9 = 3?
3 из корня 5 будет 5 если мы взять формулу в квадраты
то есть ты вычисляешь BO по теореме Пифагора
да
почему бы об этом сразу не написать?
было бы и лучше так
короче, значения BO и tan(BAC) у тебя правильные. проблема - с оформлением
Да, у меня получается большой кошмар на доске в школе, хотя решаю правильно
Спасибо за обзор зато
в работе было указано нецелые ответы писать десятичными дробями? если нет, то я бы записала ответ как 1/2
Видно, что не указывают, в какой форме записывать ответ, так что я написал в десятичных
лучше так не делать
простые дроби предпочтительнее
особенно если что-нибудь типа 1/3...
понятно
теперь формулировка лучше?
в четвертой строчке в пункте 1 вместо плюса должен стоять минус
вот так нормально
понял
to determine the highest value of 2sin(3x)+cos(3x), do i have to take the derivative and then look for max min values or is there a more efficient way?
Ann
thanks!
why was angle 60 chosen here?
cuz theta' ig
Line h goes through point (0, -k) and has a gradient of 1. If that line is tangent to the circle which equation I already sent above, then the value of eight times all possible values of k is?
the radius is an imaginary number which means the circle doesn't even exist, but can you get the answer anyway?
here's the slope intercept form of the line
then just substitute it to the equation
and since the line is tangent to the circle, that means the discriminant is equal to 0
and the value of all possible ks multiplied is
since they ask for the value of 8 times all possible values of k
is this a valid answer?
#3-12
try to show some effort, or at least split the questions, it'll help you to get help
okay
wait wdym split the questions
like put it in sections
?
post only a single question, solve it, then post the next one, not all in one like you did in the image
okay
this is kind of silly but does anyone understand what this question is asking me
Hello, I am just a bit confused, in the textbook (french) it says that the value of the angle between vector u and vector v is 7pi/12; But I don't see how
It says that the angle between two vectors is the smalles angle theta when they have the same origin
take hight as Y and t as X and do the quadratic formula
No i meant c in specific
do you have the answers?
no
well i would do t=0 idk about what else we could do
Anyone who knows the name of this figure? It’s supposed to be a topped off cone with a curved side
lets say sinx = a so the question becomes a quadratic formula:
6a^2 - 5a + 1 = 0
if we solve for a we get 3a = 1 and 2a = 1 so a= 1/3 or 1/2
don't do people's work for them
for 12
from the B point draw a line to |AC| so that it makes a 90° angle lets call the point that it contacts as D.
DBC angle is 45° and you can try to find |DA| from 30 60 90 triangle and get |DC| along with |DB| and find tan45
alright, im sorry
again, don't do people's work for them, not to mention this is not correct
dang 💀
lmfao
How would one solve a problem like this
It's between pi16 and 324 if that helps at all
Idk how to solve it though
you can break the shape like this
shouldn't be that bad from there
wait nvm
hey why cant arcsin have its range restricted to [π/2,3π/2] instead of [−π/2,π/2] it would still be injective right?
do you mean [+pi/2, 3pi/2]?
yeah my bad
well you could take the inverse of the restriction of sin to [pi/2, 3pi/2] sure
that exists
it's just different from the canonical restriction
and is somewhat less elegant
i see.. so its just a convenient convention of sorts right?
essentially yes
alright thanks!
that is identity rule ? sin(a+b)=sinacosb+cosasinb
but why ? why just not sin (a+b) = sin(a) + sin(b) 🙂
Why not?
sin(a+b) = sin(a) + sin(b) is simply not true lol
sin(90°+90°) ≠ sin(90°) + sin(90°)
“Hey god why didn’t you make sin(a+b)=sin(a)+sin(b) that would make things so much easier bruh”
Just like (a+b)² = a²+b²
It would be pretty, but it's not reality
Not to mention, that would imply sin(x) = λx for some constant λ
Which would bode ill for the shape of circles as we know them
Higher than snoop dogg
are supplementary congruent angles right
https://en.m.wikipedia.org/wiki/Pitot_theorem
@aakhilv#0001
In geometry, the Pitot theorem, named after the French engineer Henri Pitot, states that in a tangential quadrilateral (i.e. one in which a circle can be inscribed) the two sums of lengths of opposite sides are the same. Both sums of lengths equal the semiperimeter of the quadrilateral.The theorem is a logical consequence of the fact that two ta...
does anyone know how to approach geometrical questions that want you to proove something
i look at the question, i think about how i can solve it
no methods help
then i look at the solution and it seems so obvious
send me one of the questions
Aight
Prove that the centre of a circle touching 2 intersecting lines, lies on the angle bisector of the lines.
do you have a diagram
The question doesn't have a diagram.
Can anyone explain me how to calculate side BA please?
BAC and BAD are both right triangles, if I am reading this correctly. AB is a common side. You should be able to use a system of equations to represent the situation.
Is the answer 1 line?
Yes.
can some one help me to find the measure of the angle between the diagonal of trapezoid inscribed in circle?
what did you try?
you were on the right track using cos
what's the equation with cos from soh-cah-toa?
right, and what is it in your case, with those labels
I mean write the equation about cosine
with your given diagram
similar concept
write out the cos equation you would use to solve for x
are you still on this question?
you’re just solving for x right?
you’re not going to use inverse cosine (cos -1) when trying to figure out a side length
should look something like this
you only need to do inverse sin, cosine, or tangent when figuring out angle measures
side lengths are simpler
^ that's the way
that’s good, the more practice, the better
yea what you have in looks right
the horrors of deltamath
i gotchu
im in algebra 2 so im not 100% sure but add all those degrees up and is all equal to 180
and solve for x
YOOOOOOO
motherfucker this a test?
<@&268886789983436800> not sure if it's a practice exam or smthn?
but ig i should ping
banned
To locate a whale, two microphones are placed 6000 feet apart in the ocean. One microphone picks up a whale's sound 0.5 second after the other microphone picks up the same sound. The speed of sound in water is about 5000 feet per second.
a. Find the equation of the hyperbola that describes the possible locations of the whale
b. What is the shortest distance that the whale could be to either microphone?
it was a practice website called deltamath…
can there be an algebraic expression for
cos(20°)
i don’t care how complicated it is, as long as it uses all real numbers and functions
like how cos(45°) is sqrt(2)/2
something like that, but for cos(20°)
I'd probably look at trying to work something out of the real part of the corresponding cyclotomic polynomial
cos(20°) is the real part of an 18th root of unity, so it is certainly algebraic.
However, the minimal polynomial for cos(20°) is 8x³-6x-1. It has 3 real roots (namely the real parts of the other primitive 18th roots of unity), so it is a casus irreducibilis where the roots of the polynomial cannot be expressed using real radicals only.
I’m quite unsure tackling how to solve for X when it’s in the exponent
In example, “Solve for X” 10^3x=25
That's not even an equation.
Oop
Brb
It says round nearest hundredth
Do I begin by cube rooting ?
I got log(2.92)=X
X=0.47
I’m not sure if it’s correct or not
Punch it into a calculator and see if you get 25 as you should.
Yeah sort of
But closer than either 0.46 or 0.48 gets you.
You get a slightly nicer expression if you start by taking the logarithm: log(25)/3.
(Which of course has the same value).
Oh ok
chat any idea how i can get AE if i have AC equals 25? (ignore the writing down there)
chats dead
oh what’s up
AE is proportionate to AB as AD is proportionate to AC
that’s about the only way i see it
Yo I’m in accelerated algebra 1 and I might take geometry next year is there any thing I should know before hand like things that are gonna be annoying
just pay attention in class and you should be fine
depending on the teacher u might have alot of memorization as theres a decent amount of theorems and angle relationships
Guys do any one of you have, the formulas of triangle
Like
Areas
Similarities
Medians
Bisectors
And plenty more, all in one file ?
<@&268886789983436800>
tagging 8 times
why are you pinging random people?
man
that was quick
is it possible to solve binets formula for x
it’s like
coukd you solve this for n
this but multiplied by cos(pi•n)
What do you mean by solve here? If you have a large Fibonacci number and want to know which it is, in practice you can just ignore the ((1-sqrt(5))/2)^n term -- it goes to zero for large n anyway.
Hint: It's a red herring that one of the lines goes through the center of the circle.
I can't understand those two different question can someone help me plz?
What it supposed to be 148 degrees?
What don't you understand ?
Let's start with the first one @rocky tide
Ask anything.
I need help with this
How would that help? I tried it
X= 60°
Oh I was just going to say that lol
I noticed that it did make two 30 60 90 triangles
Tangents that extend from the same point are identical
I didn't see that at first
They form identical triangles
And from this we extract the following
x+β=180°
β is 120° in our case
Is the first one good
cos(30°) = MN / 10
10 cos(30°) = MN
10 (0.866) = MN
8.66 = MN
Yes
How to work this
You try to find X?
I think so
Because there is no question. I'm assuming you need to find value of x
Yeah it should be it
Thx man but if I get the question in sin=but in fraction will it work with the formula u make.
Since we know Hyp and an angle and we need to find adj,we take cos40°
What do you mean?
If you get sin then you have
Sin40°=BA/10
Like the question is similar but just numbers are in fraction
Oh
Ohhhh thx man
Np
I got 15/17 X180
=2700/17x1
=158(14/17)
Then we take the formula
What? 15/17 is the cosine, not a fraction of a circle (or of a straight angle).
You don't even need to know the angle in degrees because the problem is telling you the values of all the trig functions.
Oh yes
The only thing you need to do is know which of them to use.
Oythogoren theorem
Pythagorean? Not even that.
Cos =adj/Hyp=15/17
And then replace Hyp with 34 and adj with y
If I remeber correctly
y is the side opposite to angle A, not the adjacent one.
Then take sin
@rocky tide, are you still here?
Yeah
My level is grade 9 so by far in trigonometry I had learn Pythagoras theorem
Sorry,I thought that the angle was 15/17 rad. My apologies
You don't need Pythagoras for this, but you do need to know what sine and cosine are.
How to solve then
SinA=opp/hyp
Is the answer circle?
Yes.
Thanks
Then x 180
SinA=y/34
No, there's no 180.
just isolate y
The 34 need to be divide by a number right
Just gave you the solution.
It's not good to go all the way to a complete answer just because the asker isn't getting it.
^
@rocky tide I'll write it down again :
sinA=opp/Hyp(1)
sinA=8/17
opp=y
hyp=34
So we put all of these at (1) and solve for y
So y=16
No it's 8/17=y/34
Yes.
Yes,you got it

I need help
look up the inscribed angle theorem and use properties of triangles for the rest
Is the answer 30?
Wait I mean 20
Wdym checks out?
oh
yeah
it's 20
lmao
i think you're supposed to use something much simpler than inscribed angle lmao
Lol
inscribed angle is one of the simplest things to apply
im 99% sure they're meant to use basic trig lmao
Could you show the solution you think is simpler than the inscribed angle theorem?
by simpler i mean uses just trig and properties of triangles
I don't understand what it is you're proposing.
What could possibly be simpler than "divide this number from the figure by two and you're done"?
im not proposing anything, i'm just saying that i think they were expected to use just trig and triangle properties to solve
bc ngl im not sure if this guy is taking ms geo, but when i was, i didn't know wbt the inscribed angle theorem at all
You're saying that you think they are supposed to use a method that you refuse to reveal what is?
Can someone please check a problem for me quickly?
ok so
i probably should've known better than to go about disagreeing with tropo
i genuinely thought there had to be a simpler way >.>
but i dont think it's possible to do w/out inscribed angle
my b
I need some help
draw another secant line (connecting two of the points on the circle that don't have a line between them yet), derive more angles using the incribed angle theorem (I think a pattern is showing by now), and you will be able to find x using the angle sum of a triangle.
Is it 15?
Hmm, that's not what I get, but I might be missing something. What's your reasoning?
Because it looks like two 30 60 90 triangles and 30 ÷ 2 = 15
I remembered what to do and got 26. Is that right?
seems ok now
Ok thanks
Try using sinx+sin3x=2sin2x*cosx and cos2x=2cos^2x-1, this must help
Did help somewhat but still couldn't solve it
What did you get?
4sinxcosx + 2sinx = 2cosx + 1
I would wlog z = 1 and trig bash everything.
not sure why they chose the value 26.656, seems kinda stupid.
you should've got sin2x+2sin2x*cosx=2cos^2x+cosx
Yes then I divided both sides with cosx
x=1/2(66-14)
How is that better?
because 2cos^2 x+cosx=cosx(2cos+1)
Oh damm
I don't get the result, I found the others and it shows that (x+y)/z is 1

Show your work
firstly, find angles that are equal to theta, there are plenty of them
I solved it
$$\cos(x)-\cos(y)=\frac{5-\pi}{10}$$
MiracleMan
$$\cos(5x)-\cos(5y)=\frac{1}{2}$$
MiracleMan
This is easily solvable by plotting
I was wondering if this was analytically solvable
I know 0 < x,y < pi/2, and y>x
Is it okay if I ask for help here and trig 😅
I tried using maclaurin series but nope
Holo
can someone give me the equation I can use to solve this because their explanation is bogus?
I know in this scenario
A= 18/30
B=15/30
hello, I'm having a bit of a problem on this one. If there are two equal sides/angles the "N", what should I do? My answer is supposed to be largest to smallest order
This is just knowing definitions. I could help, but I really think going back and ensuring you understood the lesson fully is probably a better starting place.
I want to calculate this integral, but could you help me with the visualization?
How could it be drawn?
it is the shape which is restricted by axis
help
9x-4=4x+2
9x-4x=2+3
5x=5
x=1
LO= 9 (1)-3 = 6
64=8+7x
56=7x
x= 8
m <NPI = 8+7x = 8+7 (8)= 64
I think
Why is tan multiplied by three and powered up to 2?
hey, I need help on some math homework thats due in an hour. Im currently in the unit of adding vectors, and we recently learned sine cosine and tangent, which we're supposed to use for this example. How can I do it?
you can use pythagoream theorem to find the magnitude of the movment
in geometry of triangle what this value mean?
Ausländer
Integrals go in #calculus . Also post the question before your solution
can someone help
can someone pls help me with this question, i've drawn a diagram but i do not think i have the right equations:
Hi, I agree with your answer. I wonder if there is a typo and the coordinates of D are meant to be (-2,-2)
they are all incorrect
im pretty sure i've seen something similar on youtube
like mind your decisions probably
what do you mean?
thats a youtube channel that makes videos on math problems
thanks
The first triangle was labeled incorrectly, so you used the wrong trigonometric ratio.
Actually, looking at it, all of them are.
The opposite side is one the angle does not touch.
Though the second triangle seems right, but you still labeled the sides incorrectly. And I think your final answer is incorrect as well.
i'm still confused
oh alright thank you
“Adjacent” means “next to”.
Many of the steps you did were right, but you just flipped opposite and adjacent when you labeled them, so you ended up using the wrong ratio.
okay thank you
like y=am+c because i don't know the y values
........
okay so that took me some time to decipher.
seeing as that's nearly a full day later you're saying this
but whatever
do i understand correctly that you have actually written down The equation of line AB is y = am + c as part of your work, or did you just blurt that out
yeah i wrote it like that
sorry it's y=-am+c because the x value is -a
also line AC would have the same equation
what is m?
i don't know i don't have any definite coordinate just variables
no like that is the equation of the lines with the information that is currently known to me
anyway, i think you're confusing the equation of the line itself with what happens when you plug one of your points into it.
hmmmm, what do you recommend that i do then?
consider point A and its coordinates first and foremost
and then the angles made by AB and AC with the x axis
right right, i am sure that i have no idea what the coordinates of point A are apart from the fact that the x value is greater than a
the medians of your triangle intersect at the origin
and the intersection point of the three medians of a triangle divides each of them in a 2:1 ratio
the lines in a triangle that connect each vertex to the opposite side's midpoint...
What “further depth” do you mean exactly
Are you struggling with something in particular?
What equations?
Well
Best I can do is to link you to some resource
https://www.khanacademy.org/math/trigonometry/unit-circle-trig-func
The unit circle definition of sine and cosine is much more general and powerful than the “ratio of sides in right triangle” definition that students are usually introduced to
So just think of using sine and cosine to solve for triangle sides/angles as an application of trig functions, not the definition of trig functions itself
true
Whereas if you look at something like uniform circular motion it’s much more sensible that the derivative of sin would be cos
Still confused by this.
I dont remember the formula on how to find surface area of cone. ;-;
Surface area is = 𝝅rl + 𝝅r²
Where l is the side of it (e.g the 11cm on the 1st one)
The 𝝅r² is the surface area of the circle face so if you cone is open at the end you don't need to use it
Hope it helped a little :)
thanks :D
By any chance they don't give you the 'l' side just use Pythagoras assuming they would atleast give you the height for it
I dont really get what it means by show your awnser in terms of pi
Oh usually your answers on your calculator will have 𝝅 with it since it was multiplied in
Just don't hit the S->D button (the button that converts fractions to decimals, still don't know the name of it lol)
Basically they dont want decimal answers
oh, okay.
I could go through one with you if you still feel lost
The diagonals in a rhombus bisect one another.
So BD = 2BE
given an arc, is it possible to construct with compass and unmarked straightedge the circle upon which it lies?
this works
i understand now
Do you have a specific question about them?
Hi, so I'm working on the first one (finished the other two) and I'm a bit confused as to what to do, even with the hints. If someone could help, that would be much appreciated
,rotate
I've been trying to solve this and i found a contradiction when i tried 2 different approaches, i cant manage to find the mistake 
This is all the information i got, heres the original exercise, (its in italian)
,rotate
"A right pyramid has as its base a square with a diagonal of 18(sqrt2)cm. The hight of the pyramid is 1/2 of the hight of its triangles, find the volume of the pyramid in exact values."
I found only 2 approaches and one of them involves trigonometry, which we havnt learnt yet.
Exact values is like 10(sqrt2) not ≈14.14
I just realised that i might be in the wrong channel
ok, so i am not sure if my approach is correct, but, the diagonal of the square should give you the side (by the pythagorean theorem) So, now let the height of triangle be y and then height of the pyramid will be 1/2 * y.
Now the centre of the square, the height of the triangle and the height of the pyramid also form a right angled triangle in a different plane.
So, height of pyramid by the pythagorean theorem, as in (1/2 * y)^2 + (1/2 * 18 )^2=y^2
solve for 1/2 y , you will get, height of pyramid
Then you can apply the formula for volume
Oh i tought i had to ask in #help
no
Oh ok 👍
(1/2 * y)^2 + (1/2 * 18 *sqrt2)^2=y^2
im strugling over here, where did you get (1/2 * 18 *sqrt2)^2
it is half of the base
oh and by hight of the triangle i mean the "apotheosis" i didnt know the word for it
what is the apotheosis?
then i think i need to think what i have done
Heres everything i tried so far (all giving me contradicting results) i have in 'a' the apothem
(Btw the dot (•) is multiplication)
The hight of the triangle is the apothem
Thats what i meant by hight
i was talking about the actual height now
The hight of the pyramid is 1/2 of the apothem of its triangles
wait i misunderstood the whole question
Oh xD
So the diagonal of the base of a quadriangular pyramid (not sure thats a word) is 18 * sqrt2 cm, the hight of said pyramid is half of the apothem of the pyramid's triangles, find the volume in exact values.
What i found is that the side of the base is 18cm, and that the triangle that forms using the apothem as a hypothenuse and the hight and half of the length of the base (9cm) as the cathetus' is a 30 60 90 triangle
Anyways i gtg
had
im going for option 3 and 4 as this is the only case where a = 2h, im strugling to understand the mistake in 1 and 2 tho
guys how do i start trignometry?
whats the best place
to start learning trignometry
thx
damn bro 8th?
me too but im learning in 9th
i just came to 9th so im still 8th?
tries to make sure that i learn hard stuff in the earlier grades
yes yes
yeah just the basics not too deep into it
Your mistake in method 1 is only applying the exponent to h, not 2h.
ohhh thx
how dis
Write the general form for all the solutions to cos0= -1/2;
based on the smaller angle.
I swear my prof didn't say anything about this s***t
is anyone here
I'd imagine it's a complete cone with the top chopped off, so you can find the volume of the whole cone and the volume of the piece cut out, and subtract it
you have to use similar triangles but idk which
yea but idk height
of the full cone
that's correct
can u tell me the sides for it
how to set it up
that’s what i said
i don’t tho
the teacher showed in class but i forgot
so like this

noooooooo
what's wrong?
probably just a calculation mistake
can you try it and see what you get
ping me cuz ima close discord
@simple rain did you forget to delete substract the volume of the smaller cone?
hiii can anyone help me with this? it’s geometry snf it’s surface area of composite figures
divide and conquer: outer curved surface area is $2 \pi r h$
vin100
upper and lower surface area is circle's area minus that of the square
inner surface area is four times each rectangle $sh$, where $s$ is the side length of the square
vin100
it suffices to establish a relationship between $s$ and $r$.
vin100
i need help with something in my geomotry
you comfortable with sine, cosine, and tangent?
the “0” is called theta and it’s just a variable
same for x, y, z, or any other alphabetical letter
so no help?
is there someone here who specializes on geom?
?
khan academy
ive never used it
search up the concept on google or youtube idk
do i upload picture?
no it just teaches you the basic concept
good luck
ty
what question are you referring to in the worksheet?
i think it's 53
i also got 53
but im not sure if the angle is supposed to equal the bigger arc
i was absent a day and the teacher didnt teach me just gave me notes
equation is angle = 1/2(151-45)
why 1/2?
thats the theorem
i did —> angle= 151-45/2
well that doesnt equal 53
unless u mean (151-45)/2
which is the same thing as mine
the first question
oh yeah
Can someone give me some tips for memorizing the unit circle? I've got an exam next Tuesday (pls ping me)
whats the unit circle @plucky mantle
write down what u know then memorize what u dont
then repeat until u can write the whole thing
idk im doing geometry rn i just looked it up
i didnt learn it yet
u need to memorize this whole thing?
i would just print out a tiny version of it and place it in a pocket at that point ngl
when do u learn that
idk
no
i havent
is that precalc or geometry
@vestal siren when you’re finding the angle measures, use reverse sine, cosine, or tangent
don’t base the answer off of another angle measure you figured out in case your solving is inaccurate, stick with the information you’re given
ohhh
Can someone help me with the vocab ?
-
A (blank) is the set of all points in a plane, equidistant from a given point called the center.
-
A (blank) is a segment whose endpoints are the center of the circle and a point on the circle.
-
An angle whose vertex is at the center of the circle and whose sides intersect the circle is called is a (blank).
-
A chord that contains the center is called a (blank).
circle, radius, central angle, diameter?
ok ty lad
👍
can someone check something for me

For x, what type of triangle is it?
nvm i got it
ok
Yes, includes trigonometry too.
For next time use Pythagorean theorem then use arcsin, arccos or arctan (sin^-1, cos^-1, tan^-1)
To measure the angle
Or the law of sines
That too
when do i learn it
ok
u can read about it if ya want
help
is this valid for all integer p
$\forall p \in \mathbb{Z}$, $cos(2\pi p) = 1$ and $sin(2 \pi p) = 0$
yeah right?
just wanted to confirm cos me bad at trig
texaspb
first one yes
second one yes
second one could instead be sin(pi*p) = 0
texaspb

the fundamental thing to know is they both have a period of 2pi
so you can always add or subtract an integer multiple of 2pi from the argument
I wanted to check if $cos(2\pi p + \theta) = cos(\theta)$
texaspb
this is vewy important for me to understand a thing here
cos(x)=cos(x+2pi)
perfect
thanks
yw
What did i do wrong?
what you did wrong is that you assumed the point was in the first quadrant
there isn't just one angle that satisfies tan(theta)=sqrt(3)
How do I find the other angles that works?
try to solve the equation tan(theta)=sqrt(3) generally
and then choose the angle that would satisfy the following condition
Im not entirely sure how to go about that. I assume it would have to do with the range of trig functions?
So if my assumption is correct, then my other coordinate would be (5,-pi/3)?
not really
and no
that's in the fourth quadrant, which is also not where the point lies
you can search further into this since i dont have a lot of time to explain, the equation tanx=a has the general solution x=arctan(a) + kpi where k is in Z
and then just restrict this to the interval [0, 2pi], and then choose the appropriate angle
Alright, ill look into it, thanks
Can y’all help me on this
do not ping everyone.
My bad
sorry we're here to do your homework
we're not here to do your homework.
I said help
my bad +1
Not do
in any case
there are two parts to this problem
one about the length of BC, the other about the area of the whole thing
I’ve been stuck on this for an hour
which of these would you like help with?
if both, which one first?
I just need some tips
what? the question writer has spoonfed students with answer? sosad 😦
you're supposed to find the length, but he/she has just stated that
and ask for an explanation for that
there are two parts to this question. would you like to get help with part a first or part b first?
ok
so look at the diagram
just use symetry
Thanks much appreciated
what are you thanking us for
i for one havent even started
i was gonna take you through it
For youre time
upper & lower half symmetric
do you want to continue?
Yes
ok
ok so you see how the shape is rectangular all throughout, yes?
so if you were to connect C and F with a straight line, it would be aligned with BC and FG
hence the line segments BC, CF and FG add up to the height of your shape, which is 20 as the diagram says
do you understand this
therefore
no
x is just x
it is just a number, and all your work will involve expressions in terms of x
the line segments BC, CF and FG add up to the height of your shape, which is 20 as the diagram says
do you understand this
what did i say?
did i say they were all 20 or did i say they added up to 20?
well that answers your own question now doesn't it
divide what by what?
...
ok you know what nevermind
Hi, I asked this ques in a help channel, but I'll put it here as well since it is to do with trig
Question: I'm trying to simplify it and get it into terms of one trigonometric function
I know tan x = sin x / cos x
I also know that it is the same as: tan x * (1-sin^-2)^1/2
so I get to the stage tan x * (1-sin^-1 x)
but every step after this I get confused
could someone offer some guidance, thanks, ps please ping @ me if you reply 📐
Well...let me give u hint...sin^-2x means 1/sin^2 x....now we get within square root...1-1/sin^2 x ...again...there's the other formula of trigonometry...sin^2x+cos^2x =1 ..try and see if u can utilize these infos
hi, I was wondering if "sec = sin^-1" or if they're different. Thanks in advance.
The notation sin^-1 is almost always used to denote the inverse function of sine, not for talking about 1/sin(x).
This is inconsistent with sin²(x) meaning (sin(x))², but that the convention we have, like it or not.
So, if I have the Adjacent and the θ of a triangle, but my calculator only has sin^-1, then "(sin^-1 θ) * Adjacent ≠ Hypotenuse"
Yeah, definitely not the same thing.
And not just because sec is the recprocal of cosine rather than of sine.
Your calculator ought to have a way to type adjacent / cos(theta), though.
huge thanks
can anyone solve x for me?
idk much but i do know theres the right angle which is 90
add 90 + 42
then substract by 180 to get your third angle
damn it says trig ratios
mb
all good
Use a tangent with 42°
Then remember TOA
I really don't understand, im sorry
Tan(angle)=opposite/adjacent
What side is opposite from 42?
What side is adjacent?
That's okay! We're solving for x, and given an angle of 42° and a length of 5. If we can put these 3 terms in one equation, we can find their values relative to each other.
Since this is a right triangle, we can use the trig ratios to set that equation up.
From the angle of 42, we have the hypotenuse above it and the adjacent side, 5 below it. To it's left, we have the opposite side, x.
The tangent of this angle is equal to the ratio of the opposite side over the adjacent side.
tan(x) = opposite/adjacent
tan(42) = x/5
Multiply both sides by 5.
(Move the 5 to the other side while observing sign rules, that's how I think about it)
5*tan(42) = x
Punch the left side of the equation into a calculator, round to the nearest tenth as the question asks, and that's your answer.
Phew
@umbral radish
Great explanation, man.
Hello
hey
I have normalized coordinates from -1.0 to 1.0 for X and -1.0 to 1.0 for Y
-1.0 X is left, 1.0 X is right, -1.0 Y is down, 1.0 Y is up. I want the center of an euqilateral triangle to be on 0.0, 0.0, the lower left point to be on -0.5, 0.0 and the lower right point to be on 0.5, 0.0
Which one of these methods best represent the center of the triangle in this case?
My idea was to get the height of the triangle whichs is sqrt(0.75), to divide it by 2 for the Y position of the upper point and have the negative value (-sqrt(0.75)/2) for the lower points
this is the result of that
and these are the coordinates I chose
Another person used these coordinates
which had this result
And says that his triangle in the center
Does anyone know which one is actually in the center?
Btw the triangle is equilateral
but dont confuse between arcsin and csc
another way to check the center is by taking 30 degrees from each corner and draw a line. whereever all ur lines meet, that is ur center
Yeah, thanks!
Hey. I'm trying to solve this problem. I drew the radii and prepared the triangle shown. I found that $r = \dfrac{3a}{8}$. I've tried using trigonometry in different ways and I keep finding that $x = \dfrac{18a}{25} = 0.72a$, but the answer says $0.6a$. This is not homework, this is problem 206 from Solving Problems in Geometry by V. Gusev, V. Litvinenko and A. Mordkovich.
EvilSonidow
can someone show me how to get the answer for this or point me in the right way?
Nevermind, found the answer. Using similar triangles you can show that $$\dfrac{x}{a} = \dfrac{r}{a-r},$$ and since $r = \dfrac{3a}{8}$ it follows that $x = \dfrac{3a}{5} = 0.6a$.
EvilSonidow
Hard to understand what is asked
Angles E and B are inscribed in the circle and "see" the same arc CD. Use inscribed angles https://en.wikipedia.org/wiki/Inscribed_angle.
the area of the trapezium
I've used pythagoras theorem to calculate the side and the area of the first two triangles, but the third one is missing it's height
I get that but whenever I set them equal to each other and solve i dont get the answer given on the answer key
Do you mean x or did you substitute back to find the angles?
It asks for the measure of the angles
What x did you find?
The equation is $2x^2 -2 = 10x-2$, where did you go from here?
Basically, I've found the area of the first triangle, but now I need to find the area of the last angle in order to sum it up and get the area
EvilSonidow
i got all the variables on one side and then i used the quadratic formula
Since it's a trapezium the bases are parallel. Extend the smaller side and draw the height from the lower left point to create a right triangle with hypotenuse 10 and one angle of 30°.
no wait first i factored out the 2
No need for that
$$\begin{aligned} 2x^2 -2 & = 10x - 2 \ 2x^2 & = 10 x \ x^2 & = 5x \ x^2 -5x & = 0 \ x(x-5) & = 0 \ x & = 0 \ x & = 5 \end{aligned}$$
EvilSonidow
Naturally $x=0$ doesn't make sense.
EvilSonidow
Can't see anything
ohhh
that makes a lot of sense actually i see what i did wrong
thank you!
This is wrong, you can't be sure that what's left on the largest base after dropping heights is 6
This isn't what I told you to do
yes, this is what I did initally
Like this?
No, like this:
Crude drawing but you get it. Use right triangle trigonometry to find height AE and therefore find the area
which program do you use for that?
the AE height will be 5, as the angle is 30 degrees, therefore the opposite side must be the half of the hypotenuse
Exactly
but for the leftover triangle, what width will it have if it's 12 in total?
Doesn't matter, you don't need it for the area
Really? So it's not included in the area?
No. You would need it for perimeter, but since it's area you don't need the length
Do you know the area formula for a trapezium?
then it's all simple, base times height
That's for a rectangle, not a trapezium
If we find out the area for the right triangle, we need multiply it by four, since there are four of the right triangles
No, there are not
At least there are not 4 congruent right triangles
You are very close but you're using the wrong formula
the area will be the sum of the two pararells, then divided by two and multiplied by the height
Yes
Alright, thank yoy for the info
It's my first time calculating the area for a trapezium
our school doesn't go through it, I have to get maths from the internet
Yes
Knowing "cot theta is undefined" and "theta is between pi/2 and 3pi/2" allows you to deduce exactly which number theta is.
Is this an exam?
Naw it’s not
Do you know the formula for arc length?
No what is it
,,2πr(θ/360)
Lidoh
There we go.
Aii what’s next
You have a radius, r, and an angle measure, θ.
You can just plug them into the formula.
Idk where to start with this problem
do you know what standard form is for equations of circles?
Here's the question, let me get my work.
At first, I thought the areas of these were related but I'm pretty sure they're not. I would say something about trying to relate the lines which bisect these angles, but yeah I don't know how to prove that they go through the centroid of WXYZ.
@sweet whale go to an available math help
what?
8^2 + 6^2 = c^2
its a right triangle, so you can use the pythagorean theorem to find the third length
🫂
help me pls
180 - (19x+3) + 6x + 15 + 9x + 16 = 180
There are a ton of resources covering the proof. You might want to start with a Google search unless there is something specific you don’t understand.
Anybody know of any cheat sheets for all conic sections?
Can someone help me with the top equation, I’m kind of confused what identities to use to deduct sin(x+y)/cosxsiny to 1+cotxtany
I mean, you've already completely 90% of the solution
if it helps, split the numerator and distribute and denominator
side note, the denominator must be given as sinxcosy
or else the identity is wrong
Hmm
I’m still kind of confused is it possible if you can write it out
Because after I cross out the denominator I’m stuck and can’t relate back the the other side of the equation
Ohhhh ok lemme just eat dinner
Look up trig identities and keep trying meanwhile
Never mind I got it
hi, is there an English name for this formula:
https://zh.wikipedia.org/wiki/定比分点公式
$${\overrightarrow {AD}}={\frac {|{\overrightarrow {CD}}|}{|{\overrightarrow {BC}}|}}{\overrightarrow {AB}}+{\frac {|{\overrightarrow {BD}}|}{|{\overrightarrow {BC}}|}}{\overrightarrow {AC}}$$
vin100
I'd call it something like convex interpolation, but that's not an already established name.
A circle tangents the line 3x-4y=0 at the point (8,6) what's the midpoint of the circle? It also intersects the positive x-axis
I solved it to y=(3/4)x and chose origo (0,0) then found the midpoint between the points I got (4;3) is that right?
I feel like it's too good to be true and a much harder process
You mean the centre of the circle?
"tangent" is not a verb by the way
a circle constructed with its center at (4,3) will be cut in half by the line, so it can't be tangent to it
also it's not gonna be unique if it only intersects the positive x-axis, since there are many circles that are tangent to the line and intersect the positive x-axis, but it would be unique if it was required to be tangent to the x-axis
Idk the verb in English
I guess intersects?

