#geometry-and-trigonometry
1 messages · Page 105 of 1
No exercise, i just gotta learn it for my second year high
that makes it a lot harder then 
Its ez tho, give some tasks, even ones from google
Yup, hence why I was surprised
do you not have a textbook? 
Ehh.... ( ^ω^ ) Dad burns them after second year
im sorry WHAT
Fire starting material
I see
thats kinda crazy
( ^ω^ )
ω<
Ik
But its not like i can learn anything from them
.<
lol, same
My drawings are more of an suggestion
do you study for an exam?
Dad js burns em
Rn i study for all exams upcoming in second year
hmm
Thats kinda.... too much. At least for me
do you not have a teacher
it also depends on what do you search and how
if you have exams you gotta have a teacher
fair
Its summer brake >ω<
also, tell your dad to stop burning textbooks
why do you study then 😭
you never know when you need to look at them again, from my experience
To be ready
may be a good idea
Do you know the topics?
Look up and see why
as long as you have a good teacher, you'll be fine!
a responsible instructor can explain things from bottom to top
well
Not really, i just recently learned pemdas and Bodmas
that's prealg, not geo
Kimda
okayyy
Most teachers here js say, you should have learned it in elementry
true
what geo topics youve learned?
I know, js showcasing how utterly far behind i lack
None
oh uh
best advice i can give you is to get your hands on some practice probs
and do them
🥀
Idk how to thats the problem 🥀
agree. Once you do them you will know where you have difficulties and what you need to study Alex
Its giving my teacher vibes
Looked online?
For sum reason
Why?
where have you looked?
Wiki
you can download things
outside of it?
I have 11mb of storage left
Some fishy site
its actually good link, though never heard about this website xD
I have the app and idk where to go for what 4/10
Imo
There are some good sites where you can find useful info. Or you can always look for good, old books in your local library
:0 youve never heard of khan academy?
ermmmm..... no 👉 👈
I am not, so ig thats why
Local library quiet literally and phisically doesn't exist in my town, if it did i wouldn't be here (🌧️ ω🌧️ )
😭
icic
lol
European here that was neglected by corruption btw
I tried those math apps that suck
I got lost in Khan academy menus and options cuz i dunno what means what and where it takes
you must live in a very small town
How long have you tried to figure it out ? It took me some time and was confusing ngl. Though it wasn't super hard
By population it has 3k ppl, so no, phsically yes, most land is taken by private investors due to good real estate position which allows for lower fuel costs to transport materials and faster delivery to capital
Mhmmm. I see
You just said you didnt know it existed 🥀
Yes. So I just clicked on that link and went there
Let me guess, 2 monitor build?
One monitor
Bruh. I had that as my first phone 💀
Lol
No joke
💀
Imma add you as bro if you dont mind
i believe this belongs in #prealg-and-algebra ?
by adjacent you mean share a common side?
Is there someone here?? I am in the mood to solve geometry problem
I have one
Let mee see
O_o
try to solve it
6
correct
I let EH=X and GH=Y
So....
Using similiar triangle theorem
Thank you, that was fun
its EF actually
np glad you liked it
do math?
Yes
yes
I wish i could teach someone in real life
I like math too
sure
I see this impossible.
it's even easier cuz you know one side
wait nvm
yea
I am at hospital
And the only healthy thing i could do when playing is solving matu
What the fuck lol
Hello
yo i need help with homework can anybody help me?
Which class
just post your hw question(s)
!da2a
No need to ask “Can I ask…?” or “Does anyone know about…?”—it’s faster for everyone if you just ask your question! See https://dontasktoask.com/
When it comes to basic trigonometry, valuing values of π/3, π/6, etc. would it be advisable to NOT use a calculator to help with conceptual understanding?
I use calculators to utilize trigonometric functions every time, but I'm afraid it's hindering my understanding
Honestly the trick is to realize it's symmetric and the only quadrant that matters is I
then forget about tan, cuz you can figure out tan as sin/cos
Then realize that 0° and 90° is utterly trivial
do the only interesting angles are 30°, 45°, and 60°
Then remember euler formula with e^{ix} = cis(x) = cos(x) + i sin(x)
and i is the vertical axis
So cos is the projection onto the x axis, and sin is the projection onto the y axis
and the three values trig functions take for angles of 30°, 45°, and 60°
are √1/2, √2/2 and √3/2
and then you can just eyeball what the correct values are
I see a lot of math papers suggesting to memorize the unit circle, but I'm wondering how understanding these concepts can differ how I look at trig completely
e.g. cos(30°) = √3/2, sin(30°) = 1/2
I can see the π/n is used for its elegance
I'm revising trignometry for pre-calculus by the way
Well pi/n is just = 2pi/2n = (1/2n) 2pi, so it's 1 2n-th of a full turn
see tau manifesto lol
Trig is necessary for calculus
annoyingly
You have to be pretty good at it
Yeah, I totally see, my fear is how I always use calculators for trigonometric functions, that I might have knowledge gaps or problems with differentiation rules and their interworking
It's mostly trig identities specifically
and in the US, you should also learn identities involving csc, sec, cot
Looking at this table, it seems deceptively straight-forward, I can't say for certain until I give it a hand https://en.wikipedia.org/wiki/Differentiation_of_trigonometric_functions
The differentiation of trigonometric functions is the mathematical process of finding the derivative of a trigonometric function, or its rate of change with respect to a variable. For example, the derivative of the sine function is written sin′(a) = cos(a), meaning that the rate of change of sin(x) at a particular angle x = a is given by the c...
But thing to note here is that there will be more complicated integrals
where you would have to manipulate trig function sums/products into a form that's actually easy to integrate
In hindsight, I think it's quite interesting how this expression these make visual sense
$$ \frac{d}{dx}(sin(x)) = cos(x) $$
Kolo
how do i do this question?
are you prepping for jee by any chance
since this has been asked before
also the way to solve this is like, from 0 to pi/4, tan is from 0 to 1 and cot is from 1 to infinity
try to use this
no lol js trying to improve my trig which i feel im highk weak at
ah okay
the simplest way to solve is to just assume an angle between 0 and pi/4 and compare the 4 expressions
that would be considered a valid solution right? or would u have to somehow prove for all theta within that domain
if you just want the answer, assuming the values will work, if you want to show how, you have to use what i said earlier, this thing to be precise i think
Yeah this is what I did so far
yes, now see t1, t2, t3, t4
lets say tan is small and cot is large
t1 is small^small
t2 is small^large
t3 is large^small
t4 is large^large
you can see that t4 is the largest
yep!
thanks for the help
np!
t1 smollest and t4 greatest t3 is larger then t2
cause however smol tn(theta) is the value of t3 will never go below 0 cause if u keep taking roots ur min is 1 while t2 is like fraction to the power of a real number greater than 1 which jut results in a smaller fraction
OH RIGHT AM DUMB
ye ok its this
i checked smol and big for those but not t1 and t4
Hey, I was just looking at this ques, am just learning intro. to trigno. but if you mind than can you tell that how t1 was greater than t2
tan theta is a fraction
so fraction power fraction is basically like a root of the fraction
why increases the value of the farction
fraction*
but cot theta is a number greater than 1
so fraction power a number greater than 1 is a lesser fraction
like their definition or what they are?
No, literally, i didn't quite come up with a way to mathematically formulate this question
Sin
cos
Tan
Csc
Sec
cot
But there has to be some way to classify all of them
surely
Like i think we can limit ourselves to sin, because we can construct the rest from it
Okay
yes that can be done
It should be something like "what are all the expressions in sin(x) that are always true, that wouldn't hold with a general f(x)"
Do you know what the value of sin come from?
Sure
what do u mean by a "general" f(x)
Now that you know, how about cos?
cos is just square root of (1-sin^2(x) ), for example
I always think about triangle when it comes to know the trig identity
but it isnt quite the square root func
cause the square root func only has positive values
Like e.g. "sin(x)² + sin(π/2 - x)² = 1" holds for all x (is that correct expression for cos???), but it wouldn't for "f(x)² + f(π/2 - x)² = 1" for some f
yep
not literally shower, but yes
Good, now remember this:
cos(90-a)=sin(a)
Just that one and you will know other trig identities
So the question then is, find some way to classify all such identities
Yeah cuz complement angle in a right triangle, i get it
So how do i derive e.g. chebyshev polynomials from that?
This does not seem straightforward
so you want to be smart.
I'm just saying that they are a family of trig identities
So surely there is some classification?
I don't think so, i am still learning
What is that app name that can make regenerate graph?
regenerate?
Maybe that can help you derive things.
I am sorry, english is not my first language
like desmos?
Maybe
good luck
Tbh i have no clue if this is trivial and i'm just too dum to see it, or if that's one of those too hard to even consider problems.
Or if there is some known result i couldn't find by googling
click on mathematics here and click on show all channels
that could work
"Show all channels" won't be enough.
You need to go to the "channels & roles" screen (top of the channel list) and uncheck "hide the social channels".
Alternayively .iamnot studying in #bots
Damn I was not study
Vros
Can you say somwthing about which problem you have with it?
sin^2x + cos^2x = 1 you have sin so you can solve for cosine
Reposted here: #help-43 message
,tex \Tau
Dhairya
Compile Error! Click the
reaction for more information.
(You may edit your message to recompile.)
hey guys
is there a reason that the equations of an ellipse/ellipsoid are always equal to 1?
for a circle/sphere, for example the equations are equal to different numbers (the radius of the circle/sphere squared)
but what does the "1" mean in an ellipse equation?
you could rewrite the circle equation to read
[ \frac{x^2}{r^2} + \frac{y^2}{r^2} = 1 ]
cloud
the point is to have a standard form which you can easily read relevant information (i.e. semi-major and semi-minor axes) from
why = 1 tho?
is it just convention?
It's a convention that means the denominators on the left are exactly the semi-major and semi-minor axes.
so then what exactly does the "= 1" mean?
or does it not really have a specific meaning?
Huh?
The ellipse consists of those points (x,y) where you get 1 when you add (x/a)² and (y/b)².
?
That's what =1 means.
is 1 related to any of the semidiameters of the ellipse?
1 is the number one.
Then the denominators a and b would not be the semi-(major/minor) axes of the ellipse you get out of it.
by that do u mean they are the lengths of the semi-major/minor axes?
You can think of it as "take the unit circle x²+y²=1 and scale it separately by a and b in the x and y direction, which you do by writing x/a instead of x, and y/b instead of y".
One of them is the semimajor axis, the other is the semiminor axis (depending on which is larger).
so if it's equal to 1
then the denominators a and b are the lengths of the semi-major and semi-minor axes?
Yes.
ok, thanks
i just realized this is where the ellipse formula comes from
i am mildly stupid
Well what's the catch though?
Ya exactly, like infact an ellipse with eccentricity = 0 is nothing but a circle
Eccentricity is like the measure of deviation of any conic section from being a perfect circle
There's nothing wrong
i like more the analytic derivation of the trig function derivatives. I mean Limits are the backbone of calculus.
does anyone know anything about ALEKS placement test?
Under what condition on $y_1$, $y_2$, $y_3$ do the points $(0,y_1)$, $(1,y_2)$, $(2,y_3)$ lie on a straight line\?
the slope between any pair of points must be fixed
glass
-# I know
then it should be clear…
-# I assumed your response was you trying to help me on the problem
-# I guess I just want to gain some response for posting it
-# because it turns out to be a recommended problem in an intro chapter in linear algebra
-# because the problem is easy
-# but the problem is too simple for me to see its significance in linear algebra. Like maybe I'm missing a key takeaway
-# ig I'll cross post it on #linear-algebra
hello guys new here but is there a good video that sumarise geometry?
There's no royal road to geometry.
Khan Academy
Evan Chen has EGMO notes for Olympiad geometry
but you can't expect to have a video that summarises all of geometry
even if it were 10 hours long
and you'd still need to practice anyways
Nah i got 84/85, is it right?
correct!
Where's hyperbolic functions
probably #precalculus. or if you're doing calculus shit w them then #calculus.
Ok
Hi im 3rd grade highschool and I have problem with geometry do you have any tips learning?
Please explain your difficulties in more details.
Which topics in geometry you're not understanding?
can somone help with copying an angle in geometry
sure
Apply pythagoras
I'm way too stupid to know what this means
Do u know what's a right angled triangle?
Kinda 
Can u state it
The triangle which has 90° as one of its angles ,yea
Nw ,js try to understand
Did u understand this
Thats obtuse right
If it's over 90°
Under 90° is acute
I didnt mention anything abt the angles being over 90°
In a right angles triangle
One of the 3 angles is 90° and the rest 2 are acute angles
Can u identify the right angle in this figure?
6?
6 is a length of a side
X?
Can u plot the coordinates in the graph
That is also a length
Yes
idk then
Can u try plotting them then?
The thing is idk how 😢 I plotted this
Okayokay
The coordinate is not right ,ent we doing the previous question,this looks like a different question
So can u identify the right angle amoung these 3
Ye it is a dif I just need help idk how to plot it
No 
Alr so
For the 1st questions, one of the coordinates is (-6,2) the first one represents x axis and 2nd one represents y axis
Lemme find a vid
Ok
Then how do I graph it now
Scalene, isosceles, equilateral, acute, right, obtuse. All are types of triangles but what makes them special depends on the method of categorization. Watch this outstanding explanation.
Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/cc-fourth-grade-math/cc-4th-geometry-topic/cc-4th-classifying-tria...
Courses on Khan Academy are always 100% free. Start practicing—and saving your progress—now: https://www.khanacademy.org/math/cc-eighth-grade-math/cc-8th-geometry/cc-8th-pythagorean-theorem/v/the-pythagorean-theorem
Introduction to the Pythagorean Theorem
Practice this lesson yourself on KhanAcademy.org right now:
https://www.khanacademy....
These 2 should be helpful @untold oracle
Do u k which one is x axis and which one is y axis
Ah no,give me a moment
Okay
Learning to graph points in two dimensions using Cartesian coordinates.
Check this out
Do you know the midpoint formula
See red line is y axis and blue is x axis
Nope
Thank youuu
Yes
There’s a example
I can show
Try watching the vid,ig u xan plot from there
As for finding the midpoint,we will need formula
That’s the example
I get it
But a vid can explain how to plot coordinates
Better than texts
U dont need to
oh ok
Basically you take the average/mean of the xs and the ys.
For example, if we want to find the midpoint of (3,5) and (6,8), then we find the average of 3 and 6 (the x points) and the average of the y points. The average/mean of 3 and 6 is (3+6)/2 = 9/2 which means the x coordinate of the midpoint is 9/2.
The average of the y coordinates are (5+8)/2, which is 13/2. therefore the midpoint of these two points is (9/2, 13/2)
Okay got it
For 1st coordinate,
When u plot -6 ,u need to go 6 steps from origin towards negative x axis
When u plot 2 along y axis u need to move 2 steps from origin towards positive y axis
Ok
Well this is the 1st coordinate
Okay
The intersecting point of these 2 coordinates is (-6,2)
So here red is (-6,2)
But watching the video would make it clear,so maybe do that?
Ok I’ll watch it
I watched the video but I’m still kinda confused
Can u just show me how to graph that one it’s so that I can understand the next problem
This is the 1st coordinate
For second one (2,5)
We need to move 2 steps along positive side of x axis and 5 steps along positive side of y axis
And then the intersecting point is (2,5)
@rapid comet
Yes
(-6,2)
Ok
The green one is the 2nd coordinate
Ok
And joining red and green gives u the line
Yes
Ok now what
Finding the midpoint requires the fomula
He explained it well here
Alr
Use formula for it,did u understand what A GAME THEORY said
What is it
(-2,3.5)
Yes,i hope u understood how u got that
Yes it is
How tho
Idk it says incorrect
Xan u show me how u plotted it
Sorry i did a mistake
But understand where i did wrong
It's similar try plotting the points
Oh
Yo I got it bro thanks
I got all of them correct
Except for the one wrong question
2 things first I cant remember formulas and second like I don’t see simple solutions like I write 2 pages of equations and then I realize you could just just Pythagoras theorem
Which class you are in I feel like geometry is one of the most practical topic to learn
i dont remember the formula prperly but i gues it is ----> x coordinate = (x1 +x2)/2 , y coordinate= (y1 +y2)/2
3rd class high school (Poland)
What this website is?
@rapid comet , he might know
it's Canvas, an online learning platform schools and unis use
Thank you!
Excuse me, could you tell me how to use this?
your school needs to sign up to it
you can't access it freely
Oh, I see. Thank you for telling me that
How do you translate a logarithmic spiral on x-axis in polar form?
out of curiosity more than necessity lol
ig you transform the coordinates first to rectangular
then add to x
is logarithmic spiral something in the form of
[
r=e^\theta \quad ?
]
glass
that makes sense.
yes
r = e^(k theta)
oh yeah with k sorry
you can also have a constant out front
and there are various other forms for different spirals
for example the golden spiral can be given in polar form as
$\phi^{\frac{2\theta}{\pi}}$
Stick
Stick
note that the constant in front is the initial radius
where it's just 1 here, but could be anything
i see. graph shows it
I'm working with this problem I created.
The square has dimensions of r by r
The semicircle has radius of r
And the tangent line intersects at pi/4 radians
I've worked out the problem for radius of 1
But the generalized form is a little harder than that
what u solving for
Red shaded area
Are of the square, minus area of quarter circle, minus area of triangle.
The triangle is half of a smaller square with side length r·2·(1-sqrt(1/2)).
Found the area in generalized
This should work out to r² times the answer you got for r=1.
How sure are you about the 1/2 factor in front of (sqrt2-1)²?
because triangle
when using x and y to represent the horizontal and vertical positions
we see that the slope of the tangent is -1
and our intersect is (r/sqrt2,r/sqrt2)
gives us two equations for the same line which allow for the two intersects to be found
y=sqrt2r-x
x=sqrt2r-y
The red altitude is sqrt(2)-1, but the blue base is twice as long as that, so when you multiply them and divide by 2 you should just get (sqrt(2)-1)².
so the intersect points are x=r(sqrt2-1) and y=r(sqrt2-1)
Are you sure the red length is sqrt2-1?
Since the blue and red intersect at (1/sqrt2,1/sqrt2)
Yes -- the diagonal in the big square is sqrt(2)r, and then we subtract the radius of r, leaving sqrt(2)r-r = (sqrt(2)-1)r.
Problem 26.
Given a right triangle with the right angle at , let be the altitude. The feet of on are , respectively. Let be the circle with diameter , and the circle with diameter . Prove that:
a) Point lies on circle and point lies on circle ;
b) The two circles and are externally tangent;
c) is the common tangent of circles
d) AH=DE
e) The area of quadrilateral DEOO' is equal to half the area of triangle .
Help me do the e exercise
Area(DHF) = Area(FAD)
Area(DOH) = Area(DOB)
Area(FO'H) = Area(FO'C)
"Given acute triangle ABC, circle with center (O') and diameter BC intersects AB, AC at D, E respectively. H is the intersection point of BE and CD, F is the intersection point of AH and BC. Through D draw a line perpendicular to BC intersecting (O') at D'. Draw BB' perpendicular to DE and CC' perpendicular to DE. Prove that FD + FE = B'C'." Can someone help me with this problem?
What are some techniques to calculate arctan limits
wdym by "arctan limits"
also maybe you should be asking this in #precalculus or #calculus @simple heath
Uh limits that has the arctangente function but thanks anndreas ill do
"anndreas"?
I don’t understand why we have information about D’ coz its useless, you just need to use excircle properties for orthotriangle (DEF) and then you will easily proof the statement
do you know what perpendicular means?
if so, you should be able to find the symbol on the diagram that means two lines are perpendicular
OP up and left @obsidian harness lmao
Hey what is difference between orthocenter and centroid
centroid is the meeting point of the medians
orthocenter is the meeting point of the altitudes
@simple vigil
centroid is boring and orthocentre is goated
There's lots more to choose between if you want to be hipster about it: See https://en.wikipedia.org/wiki/Encyclopedia_of_Triangle_Centers
Hey there, I was going through some trigno worksheets and I found this question. Anyone know how to solve?
my solution if u didn't get it nd am very late (can someone verify this):
||length of tangent=2x
u can pretty easily prove that the triangle is right isosceles and sides=r-x and 2x
4x^2=2(r-x)^2
4x^2=2(r^2-2rx+x^2)
2x^2+2rx-2r^2=0
x^2+xr-r^2=0
x=-r+-root(5r^2)/2
length can't be negative
x=(-r+rroot(5))/2=r/2(root(5)-1)
then r-x=r/2(3-root(5))
so area of red shaded part= r^2-pi r^2/4-1/2*r^2/4(14-6root(5))=r^2(1-pi/4-(7-3root(5))/4)
FINAL ANSWR = r^2(1-pi/4-(7-3root(5))/4)||
oh wai am stooped
i think that works?
why is X56 not a notable point in Wikipedia smh
i would help you
but your nickname 😠 😠 😠
try finding $a^2 + b^2 = \sin^2 A + \sin^2 B + 2 \sin A \sin B + \cos^2 A + \cos^2 B + 2 \cos A \cos B$ and immediately some identities should jump out
south
the question should be cos(A - B) = (a^2 + b^2 - 2)/2 instead
@obsidian harness cn u verify?
no thx
*cos(A-B)
ite ite
x+2xcos(45°) = r
x(1+2/√2) = r
x(1+√2) = r
x = r/(1+√2)
||easier way to do that||
@fading jasper finally figured out a neat solution
construct the reflection across AE
then since CA = CB, 2x = 2y or x = y
2x^2+2rx-2r^2=0
it should be 4rx
Let f (x) = sin6x + cos6x + k(sin4x + cos4x) for some real number k. Determine
(a) all real numbers k for which f (x) is constant for all values of x.
(b) all real numbers k for which there exists a real number 'c' such that f (c) = 0.
(c) If k = – 0.7, determine all solutions to the equation f (x) = 0.
is that sin(6x) + cos(6x) etc?
or sin^6(x)
actually do you even still need help with this
just let me fail bro. 🙁
i've already fouind one solution
but i cannot find another for the LIFE of me.
What solution did you find
heron's for area, split into two triangles using a partition down from C and connect the tangent points to the partition from C and then just 1/2 b. h from there
Ok
you can notice that ||the center X of the semicircle is the foot of the angle bisector of C on AB||
actually can you use trig? I forgot to ask
Wdym
well i've done cosine rule and trig identities for my first solution
but if ur tlaking about something like sin17 for example dats a no
and also i'm sorry but i don't really understand what "the foot of" means
the intersection of that line with AB
Uh you don't need trig for your approach
oh yeah sorry i realized that it's easier to do heron's after i did that
so i just said that
oh ok
my approach would involve finding sinB
Thats the only trig part
Because you know how to calculate BX so the radius is then BXsinB
so if i understand you right
i label the center of the semi circle as X
then
draw a triangle connecting B and the top of the circle? 😭
wdym top of the circle
No just say the tangency point of the semicircle with BC is P, then XPB is a right triangle and XP is a radius so XP=BXsinB
For sinB?
mhm
lol what
no please don't say that 😭
i asked you a question and you said mhm
lmao 😭
and then trig identity ?
yes
I found 2 ways without Trigonometry
Hey guys can someone help me with this math question?
hint: there are two semicircles, combine them
Ohhh I see Thanks
can anyone help me with this question please?
draw the height of BAC
What after that?
Correct
If BC is the same as EF, can't I use EF and the angle at C, to find EC, with EF / Sin40
which = 5.56cm for EC
yes
so I got 5.56 from all that right? But MathGPT says it's 4.56cm
should be 9.68
what do you get for BC?
4.14
I'll retry it
give me a minute, maybe I did something wrong
yea should be 6.22
yeah I got 4.14
hm
maybe I forgot something
if GC = 4cm, and the angle is 50, we have the adjacent, and are trying to find the hypotenuse, in which we do adjacent / Cos50, right?
if i do 4 / 0.6428, in which 0.6429 is Cos 50, it equals 6.22, but if I do 4 / Cos50, it equals 4.14, am i doing something wrong in google using it as a calculator?
How to find angles like 20 50 70 degrees for trigonometric ratios?
you shouldn't round it off
identify the side of the right angle triangle you have the value of, and the side you are trying to find. For example, you dont know the value of the opposite side, but you know the value for the adjacent side, and you are trying to find the side of hypotenuse using the adjacent side and the angle. This is where you use Sin Cos and Tan, in this case we are using Cos. So in this example, you would put in your calculator, adjacent / Cos (x)
avoid rounding off in any case aside from the final answer
okay, thank you so much bro
np
technically we can find stuff like sin70, sin50, sin20 without any constructions. we know sin30, from which we can break it down to get sin15, which we can break down to get sin5, from sin5 get sin10 and get the rest
REALLY?
how without trig? that seems impossible
yes
could you tell me
first method
i had this same thing but my teacher told me it was wrong :(
y = 20-x
ODA:
r² + (11-r)² = x²
OEB:
r² + (13-r)² = (20-x)²
2 equations, 2 variables
sove for r and x, and diameter = 2r
why?
what i had :
apparently
my assumption for assuming the top z's are the same as the radius
oh wait
yes mb it's wrong
no worries
I mean yes the top 2 are the same length but not equal to r
is there anything we could do with that possibly
lemme think
You can compare areas!
Herons formula for the area of the triangle
unfortunately I think there are no other workarounds for this method
then split the triangle from C right
but I have another method
Then you have two smaller triangles with bases 11, 13 and heights r
Indeed
yep this was my first method!!
using areas
unfortunately the question's hard part comes from asking for anothe rmethod to solving it
that's what i'm realllyyy struggling with
Interesting
I thought you already have a trig method
yes it's the area comparison
only method i could find
Oh isn't it just Pythagoras then
yes this is also exactly my method
11 - z and z
z and 13 - z
These make up two right triangles
it doesn't require trig
the way i did it required trig but yeah if u just heron's formula then it is much faster
I see
if you want to try any of ur own methods for this issue the general answer is ||diameter = 11||
i think i'll just take the L on this question
guys
is this claim valid
if a right angled triangle can be put inside a semicircle then its also possible to put the triangle in the same semicircle in such a way that the largest side lies on the diameter
yes
can someone help me with the proof
the largest right triangles have their longest side lie on the diameter (circle theorem)
for each of those possible right triangle you can create smaller similar right triangles
it's obvious that all of those smaller right triangles will fit in cuz the largest of them fits in
hence proved
thanks bro
you're welcome
To Whoever has birthday today.
yeah mb this was the question
just the a, and b, part
can someone just clear a doubt of mine quite dumb ik but is 1/-3 same as -1/3?
yes
oh ok
thanks
There's also -1/-3 = 1/3
yah i know atleast that much hehe
you can multiply the numerator and denominator by the same number and it doesn't change the number
so $\frac{1}{-3} \cdot \frac{-1}{-1} = \frac{-1}{3}$
south
sin⁶x+cos⁶x = (sin²x+cos²x)³-3(sin²x)(cos²x)(sin²x+cos²x)
sin⁶x+cos⁶x = 1-3(sin²x)(cos²x)
sin⁴x+cos⁴x = (sin²x+cos²x)²-2(sin²x)(cos²x)
sin⁴x+cos⁴x = 1-2(sin²x)(cos²x)
f(x) = 1-3(sin²x)(cos²x)+k(1-2(sin²x)(cos²x))
f(x) = 1-3(sin²x)(cos²x)+k-2k(sin²x)(cos²x)
f(x) = 1+k-2k(sin²x)(cos²x)-3(sin²x)(cos²x)
f(x) = 1+k-(sin²x)(cos²x)(2k+3)
(a) -(sin²x)(cos²x)(2k+3) = 0
2k+3 = 0
k = -3/2
(b) (sin²x)(cos²x) = ¼(4)(sin²x)(cos²x)
(sin²x)(cos²x) = ¼(2²)(sin²x)(cos²x)
(sin²x)(cos²x) = ¼(2 sin x cos x)²
(sin²x)(cos²x) = ¼sin²2x
f(x) = 1+k-¼(sin²2x)(2k+3)
f(c) = 0
1+k-¼(sin²2c)(2k+3) = 0
¼(sin²2c)(2k+3) = 1+k
(sin²2c)(2k+3) = 4+4k
sin²2c = (4+4k)/(2k+3)
we know that 0<=sin²a<=1
0<=(4+4k)/(2k+3)<=1
solve the inequality to find the range of k
could someone tell me how the angle bisector theorem works ?
oh yeeeeee
ty
me failing to do basic math
here's the theorem
and here's a straightforward worked example
||C' is the reflection of C from the line AB
areaABCC' = 2areaABC = pr
r = 2areaABC/p||
that's basically the same sol
@teal warren https://bestexamhelp.com/exam/cambridge-igcse/mathematics-0580/2018/0580-s18-ms-43.php
question 6b, ii)
Mark Scheme of Cambridge IGCSE Mathematics 0580 Paper 43 May June 2018 examination.
the way I showed you was correct and your one actually wasn't correct
wait
Huh
Good thing I didn’t submit the assignment yet
Wow I just went through what you showed and it’s spot on
Thanks dude
Really
Just got an easy 4 marks
@obsidian harness Stellar
Yeah it makes sense why they ask for the diagonal across the plane now
Indeed!
u guys are in what grade?
Ty
geometry is hard
True
Gonna start freshman year and do Honors Algebra 2
geo is love
just a side question, is cos^2theta-1=-sin^2theta?
nvm. i didn't see the minus sign. sorry
-# therefore love is hard?
Man can anyone help me with this one
(tan theta)/(1 - cot theta) + (cot theta)/(1 - cot theta) = 1 + csc theta sec theta
Prove LHS = RHS
can anyone work with me on coordinate geometry?
!da2a
No need to ask “Can I ask…?” or “Does anyone know about…?”—it’s faster for everyone if you just ask your question! See https://dontasktoask.com/
Have you tried converting the LHS to sin, cos?
true
challenge problem: find the exact area of the green circle
is there a synth sol
he did say exact...
not sure; found it on BlueSky
In triangle ABC, D is mid point of BC. M is mid point of AD.
Ray BM intersects AC at F. Prove that
(i) 2AF = CF. (ii) 3MF = BM.
pls help
tools mid point theorem and median concurrency
do you have a diagram?
Is this even solvable by me as a class 10 student
idk
i wanted to come up with a funny sol
but there's still algebra so it's bad
||invert at the origin with radius 1
and you only get 1 parameter to solve for (x coordinate of the inverted circle's center)||
the only issue is ||you get a quartic that must have a double root. You can just compute gcd of the quartic and its derivative but it's long and boring||
But at least I get that the radius is ||r=1/4|| so since its not an ugly number maybe there's a nice sol
damn you figured it out
I actually got stuck
I would never have thought of circle inversion
I just didn't want to set 3 tangencies and die
but it's not like it's that nice anyway
I'll write the synth soon™
||Denote a=tan(x) and b=tan(3x), then your equation is equivalent to (a + b)(ab + a - b + 1)=0 and ab≠1. Then just apply b=a(3-a²)/(1-3a²).||
no
then make a diagram.
ok tbh I don't wanna spend too much time making it look nicer, so I'll just keep it like this and write a sketch
||Let the focus of the parabola be F. Let the centers of the 2 circles on the axis of the parabola be A and B and name them w_a and w_b.
A key property is that if a circle centered at Z on the axis of the parabola is tangent to it at points X and Y then FZ=FX=FY (this follows from the optical properties of parabolas).
Using that or in whatever way you want, prove that the radius of the big circle is 3/2.
Now let T be on the parabola with FT=1 and let K on AB be the center of a circle tangent to the parabola at T. Then prove KFT is equilateral.
Let the line parallel to FT through A intersect KT and w_a at D, E. Let G=BDintw_b. It's easy to see that DE=DT=1/4.
Compute BD with the law of cosines or whatever you want, and check that GD=1/4.
So (EGT) is has radius 1/4, and its center lies on BG,KT,AE so it's tangent to the parabola, w_a, w_b. So it's the circle we wanted and has radius 1/4.||
it feels a bit dumb but whatever
bruh
What is this looks hard !?
i think sl loney is good for 12
idk probably just skill issue, if you find a better synth lemme know
but I found out that in general (when the tangency point of w_a with the parabola is not necessarily at its vertex) then KT=(BO+AO)/2 and K=(A+B +2O)/4.
Oh and also, r_b=r_a+4FP (P is the vertex of the parabola)
could someone please refer me to some sort of youtube video that will teach me how to do questions like this?
desmos?
Whoever needs any kind of support or help be sure to reach out to me.
Thank you
We love to graph functions, and now that we know about the trigonometric functions, let's learn to graph those too! These are periodic functions, meaning they spit out the same values over and over and over, with a frequency that depends on the period of the function. This will be easy to understand if we have the unit circle memorized, so make ...
Can someone help me with this problem? I've been trying to solve it for a few hours and I don't know how :c.
In triangle ABC, interior bisectors AD and BE are drawn, which intersect at P, such that AD=AC and PC=CE. Find m∠PAE.
Hello is someone here I can talk to about geomtry
Oh u 😆😆
Uh! It was just the same question from earlier 😅
do you have an image
Okay I working on homework right now
What grade are you
I’m trying to learn grade 12 math
I’m in 9 rn
I kinda have it down
Like Ik how to solve some stuff but I’d like to learn more
Lol same here I started studying 11th and 12th stuff from 9th
And before that like at 7th and 8th i used to watch vids of 11th and 12th stuff tho i understood or not
TRIGONOMETRY HAS SO MUCH FREAKING HARD MANIPULATIONS
Is it just me or is it fr?
It is
Phew!
Haha
How much 11th and 12th did ya cover?
Not sure haha
Just learning WAM levels rn
Idek what they are but that’s why my teacher said
would plane tilings be best put in here or another channel?
i just created this tile and i think it is aperiodic (not sure tho)
https://cdn.discordapp.com/attachments/1375085745890398333/1412688497495769108/IMG_4871.jpg?ex=68b93430&is=68b7e2b0&hm=91a78d86e7ad2e5f8cf67b8143b3af6eaf8f8c7caeced3b99b3783c8176f5a86&
Guys I am new and want to understand all of trig is there any thing I should study because I have only covered basic trig and I think I might need it for pre calc if I even get there
organic chemistry tutor, and/or khanacademy
the latter also has practice questions for trig
Thanks a lot I will try khan academy
ochem tutor has a lot of videos breaking down all kinds of math questions so you can usually find one if you're stuck on a practice thing
I in 11
how do i do trigonometry man
By studying the theory, understanding the formulas and the rest is only practising a lot.
And, very important, knowing all the basics math (such as how to solve equations, inequalities, and I mean both first and second degree at least, computing things with powers/exponents) very well
Khan academy helps
how tf does trig even work bro they tell me oh SOHCAHTOA like wtf even is sin
wow it does this magically
or its Opposite/Hypotenuse
like why
and what even is it
skill issue
why is sin theta opp/hyp for instance
honestly idk but you can look it up
i've been dying bro i genuienly hate this
no one teaches it right
oh bro js SOHCAHTOA
like stfu
teach it properly
It's defined as the ratio of opposite to hypothenuse of a right angle triangle
so its just a ratio between 2 numbers how does that help me
or what does it tell you
That's how sine function is defined for a right angle triangle
so if sin theta is 0.5 that means that opp is half of hyp
that kind of self implies
Exactly
but why is this useful?
It's used in many places especially engineering if you are asking about real world applications
yes
Yes it is
i've seen it graphed
Yeah?
so whats the function
its just sine
The sine function?
yeah
and it has its own definition
It really depends on what x is
ion think u can represent it like that maybe?
Yeah you can't
im js trying to understand sin, coz and tan
yk how to write functions in ordered pair system?
Those are just ratios of different sides of a right angled triangle
ok so they are ratios but if they are also functions they have to be defined by something somehow
especially i saw their graphs
apparently sine is symmetrical
on y
so it has a value right
no sry
ok
Alright kid you are not getting it
Analytic Definition (Power Series)
Sine can be defined as the following infinite Taylor series, convergent for all real (and complex) numbers :
\sin z = \sum_{n=0}^{\infty} \frac{(-1)^n}{(2n+1)!} z^{2n+1}
= z - \frac{z^3}{3!} + \frac{z^5}{5!} - \frac{z^7}{7!} + \cdots
This definition is independent of geometry and works directly in analysis and complex variables.
sine is like u when construct a triangle with the given one angle as x and another as 90 and take the ratio of the opp and hypotenuse side of the triangle ig??
ye that is tru
kind of literally the definition
Sine of an angle has a limt
-1 ≤ sinx ≤ 1
u accept this scout?
why? is it a percentage?
Yes
It's not?
where percentage?
cuz why would it be limited between -1 and 1
oh wait
its cuz
hyp is biggest
always
ye
Yeah genius
Ion think you'll get it now but the angle can be Greater than 90° tbf it could be any angle
Do you know the ASTC rule?
every question in geometry u have done is actually using the modulus of the disp
no i js started learning trig
No not really

