#help-36
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What motivated this question?
what exactly
nvm
What made you think of it may be of help
idk, it just came to my mind somehow while doing unrelated stuff
That's real analysis though
Or well, calculus some of y'all may call it
can anyone give me science sv link
!occupied
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You mean #network
like this?
oh, i can just let r = -1/2, then the sum is 2/3 and the prod is over 1.
r = -0.999 the sum is 1/2 and the prod is 0
Yeah exactly
its like around -0.72
<@&268886789983436800>
well it would have to not be algebraic first!
or some combination of e and pi...
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for part a)
i showed H is in the set, using that H is non-empty and ab^{-1} is in H.
the mark scheme shows that I should've used H is closed under multiplication, the identity is in the set and the inverse.
is it okay for me to use the first method or is it better to use the mark scheme method? or does it even matter
the way you did is fine
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ap:pb
it is provided in your problem statement
lambda = l
mu = u
AP = l/(l+u) * AB
AP + OA = OP
this only has lambdas in the numerator
$\mu (\vec{OP} - \vec{OA}) = \lambda (\vec{OB} - \vec{OP})$
notasnugglebugz
notasnugglebugz
and substitution
okay makes sense
ok done?
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how do i find the asymptotes of this hyperbola
y = b/a(x) and y = -b/a(x)
well, you're given a vertex and one of the focii of the hyperbola
with that you can compute both focii and thus their distance, which is 2a
yeah the c is 13
c^2 = b^2 + a^2
13^2 = 12^2 + b^2
169 = 144 + b^2
25 = b^2 b = 5
equations are 5/12(x) and -5/12(x) ?
what are you calling c, b and a there?
c is the distance between the middle and the focii
a and b is x^2/a^2 - y^2/b^2 = -1
-1 here because its horizontale
this only applies when the major axis is the x axis
how do you need to change that if your major axis is y?
wait how do u know if the major axis is y
.
oh cause of the -1 ?
ohh
why did they put b/a(x) here and -b/a(x)
the focii and vertex are on the y axis
and its -1
because it's the solutions for a DIFFERENT exercise
see that in your case you have the vertex being (0,12), not (0,5)
ye
so they used b/a(x)
and we're doing a/b(x)
so the difference is that the y value is different?
and what they are calling b and c, probably
i call it the same way
they are calling a to the horizontal, b to the vertical, and c to the distance from center to focii
not a the distance on major axis and b on minor axis
a is 12
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What would the indeterminate form be here? I just see undefined / undefined
inf/inf
But the limit doesn't exists for either the numberator, or denominator
how so? it is (1/0)/(1/0)
from the left you get +oo/+oo from the right you get -oo/-oo=+oo/+oo
that is one of the indeterminate forms
isn't it other way around ? from the right it would be +infinity / + infniity
Oh that's interesting. So, even though neither of the limits exists for the numerator, or denominator since (LHR does not equal RHR). Since approaching from the left, or from the right both yield an indeterminate form, L'Hopitals still applies. That's cool.
+infinity / + infinity = -infinity / - infinity? we can factor out the negative and cancel?
lhopital applies for oo/oo or 0/0
even if it was -oo/oo it doesnt matter since you could factor out -1
infnity has -1 in it?
also what about this?
nvm infinity has everything
You might call me stupid #star, but that is actually cool
@left trail Has your question been resolved?
the limit exists
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how to do this
is the problem saying show this?
what
like is your problem/question you need to solve just to show that inequality
Find the domain first, then square both sides
whats a domain
note that this equation cannot be satisfied for any arbitrary x, e.g. you cannot have a negative number under the square root
i know that much
So first of all x^2 - 3x + 2 >= 0
you can also use what you've sent
i.e. consider when g(x) < 0 and g(x) >= 0
ah i know what a domain is its just called differently in my language
i dont get it
Okay, have you already determine it then?
no...
Can you solve x^2 - 3x + 2 >= 0?
using the quadratic formula?
also i have to turn it into something like (x-1)(x-2) >=0
x=/=1 and x=/=2
wait no
?
this is an inequality, not an equation
the solution is supposed to be an interval
shouldnt it be > instead of >=
No
then how is it not 1 and 2
included i mean
how are they not included
in solutions
It must be >= since it's allowed to have zero under the square root
They are
you said yes to this
To this*
This is true and it doesn't imply x can't be 1 or 2
what to do from here
e.g. for x = 1 you have (1-1)(1-2) = 0 * (1-2) = 0 >= 0 ---> TRUE
it cant be 3 for example right
i get what you mean
no wait it can be
it cant be anything less than 1
oh it cant be anything between 1 and 2
ye
but it cant be 0.5 for example right
it can (1/2 is less than 1)
so the solution is
Modus
no
from 0 to 1
i think at least
no youre right sorry
since two negatives give a positive
It's our domain
Not the answer yet
Whatever you come up with now has to be in this range
whats the next step
Notice that if x - 2 < 0, the inequality is true because LHS is always nonnegative
and hence:
smth nonnegative > something negative ---> ALWAYS TRUE
this is why we do it
what is lhs
ls
elaborate a bit more please
Can't you solve this
To this part, yeah
thank you
But it's not the final answer yet
whats the step after it
now you have to consider what happens if g(x) >= 0
yes and then sqrt(x^2 - 3x + 2) > x - 2 becomes x^2 - 3x + 2 > (x-2)^2
elaborate a bit more
a > b implies a^2 > b^2 when both a and b are nonnegative which is true when x - 2 >= 0
so what do i need to do next
@raven sage Has your question been resolved?
<@&286206848099549185>
solve for x on the right
@raven sage
ill give you good idea
im listening
u have f(x)>g(x)
study the sign of f(x)-g(x)
using derivatives way
ill write it in hand so that ull understand
@raven sage
im here
you will derivate f(x)-g(x)
yull find the derivative is always negatives so that will make f(x)-g(x) strictly decreasing
Idt this is a calculus exercise ๐ญ
but it'll lead to the point
thank you
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.
@tribal ocean
its not homework i promise
this is for practice
@raven sage as long as it makes sense though
They're basically asking you to split the logic by cases whether x - 2 is positive or negative
then solve for each case
and the reason we want to split is so we can square in one of the cases
you can't square for all x
thank you
Delete the message
what do i do now
i wanted to analyse that
man why are you doing this to me
i asked this question previously as well
like a month ago
its not homework i promise damn
Well
Let's look at what you have so far:
As Modus said, your inequality is now
x^2 - 3x + 2 > (x - 2)^2
This is from here.
ok i see
How should we go from here?
Alright nice!
So,
What's the 'final answer' to our question?
Or whats the conclusion?
Yeah I cant read it
I mean you can just type it :)
Yep ๐
is that the final answer
Yeah. The answer you put down excluding 2, that's right.
is g(x) always >= when we square both sides
I'd say yes, if you include domain restrictions.
If you have sqrt(f(x)) >= g(x), then it is true that
f(x) >= g(x)^2.
There is an assumption that f(x) is non-negative ๐
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I am currently stuck at this problem, ive thought about using a gaussian sum but then out of convenience switched to doing it in code. i dont really understand why my question is regarded as wrong.
maybe if i use 2n-1 instead of n, for the gaussian sum that would atleast guarantee its an odd integer. but to calculate it i would have to apply it on the non-sum aquivalent part as well and i would need to proof by induction ig?
(2n-1)^2*
Sorry, your code did generate an answer, so what's your concern here?
that it is wrong, which it supposedly is
"supposedly", because...?
when i type in my answer it is regarded as wrong. its a website
im typing it without exponential form ofc
why is your upper bound 359500?
does 2 steps each time, i would exceed 719k otherwise, wouldnt i?
There's a problem with your "induction" step here
and by doing exactly 359500 steps, what is the last number you end up summing
718999 the last odd number i think
what exactly?
it works ive tested it
No but what do you get
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Okay, sorry!!! ๐๐๐
Ok I misread, it seems that the induction is correct
Btw I computed it for myself, there is indeed something wrong with your end result
1 to 3/5 . I thought induction was for natural numbers
ik thats why i was asking
not a rational, 3 and 5 seperately tested, mb for poor articulation
n(n-1)/2 and other formulae are for integer n only
oh sorry
i was trying to help
What happens when f,g are int64 instead of real
maybe computation errors arise from there, idk
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Someone teach me calc form scratch
uhh i dont think we can
however you can learn it yourself
That's what school is for
and this
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???
what do i do here?? i tried like all combinations i could think of 1,2,3,4 but none seem to fit
same for squares and cubes of each and their patterns
is this apart of the unit your doing? Or is it recreational / competition stuff
competition stuff
mhm kk
is that the area or?
definitely something about multiplication i reckon cuz these numbers become bigger very quickly
its a Logical Reasoning puzzle ;-;
if it had something tangible to work with besides "find the ?" it would be at least approachable, but i think its just trial and error until something clicks
@radiant igloo hint: ||you mutiply something by 3 and then add that by something||
omg
that is so stupid
bruh
HOW IS THAT A PATTERN HOW WAS I SUPPOSED TO FIND THAT
1+4x3=13, 2+1x3=5, 3+2x3=9, 4+3x3=13?
in the country i am in they have an intelligence quotient section in the standardised university entrance exam
uhhh i think it is not 13
it is 13
thats correct
i thought it is 11
well yeah it is 13 the answer key also says 13
so this stuff is all too common
i mean apart from that crappy pattern here ig
anyways thanks!
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what's your reasoning for your answer
and if you want to know the correct way it should be doing u-sub on sin(3x)
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Just need a little helppp...
Okay so I don't quite understand how the bisector has anything to do with proving that the the two triangles are congruent..
I also don't particularly understand why SSS, AAS, SAS, etc. help to prove a triangles congruency.
so basically.. I don't quite understand any of it ๐
do you know what it means when two triangles are congruent
uhh the angles and sides are equal?
alright
we can say two things are congruent if they are (roughly speaking, im sure theres a more exact term) exactly the same
okay
so for example if you see a triangle with 3, 4, and 5 sides then see another triangle with 3, 4, and 5 sides
they are cogruent?
yes
now theres four main congruency rule theorem things that show two triangles are congruent
the first one is SSS or side-side-side which youve used above, it basically just says that if two triangles have the same three side lengths they are congruent
uh huh
congruent includes similar triangles, not only equal ones, no?
oh okay i was just a little confused since im not really good at geom as well
im not sure
uhh
anyways, if triangle 1 and triangle 2 are congruent, you can get from one to the other by reflection, rotation or moving it (not sure if scaling too. those would be similar, not sure if congruent)
this is true, but similar doesnt imply equal
so basically the triangles are just duplicates of each other?
yes
just looked it up, congruency doesnt include similarity; its the other way around
similarity includes congruency?
okay
okay... but you know how in the question it says, 'AQ is a common side in both โตAQB and โตAQC' what does knowing the common side prove?
but why do they have to go through with all the other stuff if its as easy as just saying that one of the sides are the same??
since Q is bisector, you also know an equal angle
cuz tou need 3 things being same, not 1
ohhhh
and since isosceles triangle, you also know a second angle is equal and/or side
so like Q is bisector for...
so its like there is an angle at the top with a line in the middle
OHHH
Wait...
so
becuase we have proof of the shared line in the middle, and we also have the angles at the top.. and we also have the equal sides on the outside (BA and CA) thats three things to prove that the triangles are congruent???
correct
in this case, criteria SAS
side-angle-side
with the angle being the one between sides
since congruent, all angles and sides are equal
okay ๐
actually.. waitt
Umm
How would you prove that AQ is perpendicular to BC??
And how prove Q is the midpoint of BC??
apply cpctc
sorry what is that??
Corresponding Parts of Congruent Triangles are Congruent
woah um
its reasoning
its the reasoning for when u proof two sides/angles are equal of triangles that u have already proven to be congruent
can you identify which sides of triangle AQB correspond to which sides of triangle AQC
and same thing for angles
Ohh
made a typo
Well... AB = AC (they are equal)
โฆฃQBA = โฆฃQCA (Iscocelles triangle so angles are equal)
Ugh I can't finish this now... is it fine if I leave this thing open?
channel will auto close after a while if you're not here
how long will you be gone for
@thorn meadow Has your question been resolved?
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can someone help me go through this exercise ๐ฅ
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
1
the first question is easy but it's the first time I've seen questions like the following
Sorry to interrupt but <@&268886789983436800> sean combs pfp
Tf is sean combs pfp
Yh - while that's not an explicit rule, it is in contravention of #changelog message
diddy
This
[see the changelog message I linked]
So diddy = sean combs pfp
Diddy is sean combs yes
But can we please stop and let the mods deal with this
Oh i see
But with what?
The guy
For the diddy pfp?
Ye
U cant be serious mate
tell that to the mods.
I mean it violates #changelog message
@marble cedar Read the changelog message I linked
the #changelog post was made for a reason.
/ that larp larp linked
regarding the question, and I'm afraid I'm gonna commute so I won't be around in a bit - do you recall how to test whether a function's injective (for question 2)?
you're welcome to modmail if you think it's absurd but I don't think it's productive to debate about this in a help channel.
But arent those for pedophilia accusations specifically?
@marble cedar
take this elsewhere please and thank you
just let the mods decide and let the helpee (and future helpers) have his stuff.
No Im not even per se saying its absurd Im saying ur applying the rule incorrectly
then the mods will advise.
I guess
I opened a channel and now there's a whole debate for a pfp seriously. Even in the changelog there's only mentions of calling someone else or making jokes using Sean comb or the other guy. I'm going to open a channel later this one made the question go up
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You know that the question gets pinned right?
most people would come and see others debating and probably wouldn't stay any longer, at least that's what I think. Please let this debate stop
Dont think the debate will stop
But speaking of which, no moderators actually said anything
Seems safe ig
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Is it considered mathematically invalid to rewrite the second expression like I did in red?
inยณ?
Basically what I'm asking is if cubing the denominator only is invalid, or am i required to cube the whole expression?
you cube the inches
or else you'll get a length as the result
and the imperial system isn't that weird
cube everything.
ohhh im illeriate i didn't read the question properly
the question wants cubic inches
1 cb. in. is equivalent to (2.54cm)^3. 1 in. is not.
Okay i figured out my mistake
yeah i realise that now
thanks guys
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My professor gave me that problem to solve but I just couldn't figure it out, I know that 10^(log(x)) = x so I used this so that 10^(log(2+sqrt(r))) is 2+sqrt(3) but I just couldn't understand where to go to eliminate the sqrt(3)
Obs: I simplified the whole log expression to just log just so it helps (the question is under the draft)
Girl my eyes hurt trying to read that can you increase the contrast a bit
Or maybe type out the question
yes
Suppose $f(x) = 10^{1+x} + 10^{1-x}$. Show that $f(\log(2+\sqrt{3})) \in \mathbb{Z}$
Zavier ๐บ
it's "if f(x) = 10^(1+x) + 10^(1-x) then show that f(log(2+sqrt(3))) is integer
Let's write $f(x) = 10 \cdot 10^x + \frac{10}{10^x}$
Zavier ๐บ
uhm, okay
Zavier ๐บ
Now let's sub in log(2+โ3)
yeah but then we'd get to the same place I was
I have no idea what to do with this
Well, rationalize
See this was because I couldn't read what you had sent 
Are you familiar with rationalization
sorryyyy
Don't be
yeah I just multiply by 2-sqrt(3)
Do that then
and then I'd get here
Wait
Uh no, you should get 4-3 on the denominator
Also rationalize here
Where did the 10's come from
I was with the 4+3 not 4-3
It's not 10, I mixed up again... wow
it was 2
okay
then the sqrt of 3 would be gone and it'd be 10(4) and it's40
okay
I got it!!
thanks!!!!
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. @hasty knoll post your question here
aiit
think of $|y|$ as a piecewise function,
$$|y| = \begin{cases} y & y \geq 0 \ -y & y < 0 \end{cases}$$
then differentiate each case
haseeb โฅ
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HELPPP
Asking the actual question right away is more likely to get responses.
Asking "Can I ask...?" or "Does anyone know about...?" doesn't give people enough information to decide whether they can help, and answering can feel like a promise to help with the actual question, which they might find themselves unable to.
,rccw
No
Yes this is right
Yes
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This is the full q
Iโm confused on how they did this
Conjugates, rationalise denominator
Where did the 3 in the denominator go?
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i cant seem to get any info out of the construction ;-;
are (ABC), (AMN), gamma tangent?
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<@&286206848099549185>
Menelanus theorem
Let F be the intersection of MP and AD; F' be the intersection of NQ and AD
then prove FD/FA = F'D/F'A
Do you see angle BDP = CDQ?
<@&268886789983436800>
yes
whys this sufficient?
it's easy to see that F and F' both lies on segment AD
and this ratio means that F and F' lies on the same position on AD
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stationary points include point of inflection right??
for that u need 2nd derivative and equate it to 0
but is my method correct
ah yea
for finding maxima and minima its correct
why
cuz derivative means slove of the function at some point basically
at max and min for most polynomials
the slope is 0
hence derivative is zero
but I didn't take the secon derivative
2nd derivartive accounts for the slove of the function that u get after 1st derivaton
basically like imagine if u have x square then dy/dx will be 2x
means at any point x you will have slove of x sq as 2x
on 2nd derivative it'll go to 2
means the slope of first derivative is always 2
for maxima and minima u never almost need 2nd derivative
@rain sentinel Has your question been resolved?
I mean do we classify using the hessian matrix here
or can we use a different method as shown?
i am not really familiar with hessian matrix
using differentiaiton is pretty effective
You would need to use the hessian matrix
why?
the question is just asking for maxima minima and inflextion point no?
thats just highschool diffferentiation
The function consist of two variables, so you can't apply single variable calculus
could we just evaluate at the points
ooohh wait i didn;t see it mb
How are you going to determine if a point is max, min or inflection
How do you know what is the highest or lowest values of F
I guess you could take an inspection based approach
I see what you are doing now
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I know that for $f(x)=\arcsin{(\frac{1}{\sqrt{1+x^2}})}$, the derivative can be found using chain rule, is there other way to solve this though?
Nefer
@ when reply, thanks!
There is most likely is a "trick involved" way to find it too
Triangle
Like x = tan(theta) is what I'm thinking
Yeah
;-; So how can this be done?
Triangle like before
sin(y) = 1/sqrt(x^2 + 1)
mhm
then f(x)=arcsin(sinx)
Hmm
Arcsin(sin(y)) i think
Lemme scratch it out on a note rq
\section{Question 3}
a) First, recall the derivative of trigonometric functions:
\begin{gather}
\frac{d}{dx}(\arccos(x))=\frac{-1}{\sqrt{1-x^2}}\
\frac{d}{dx}(\arcsin(x))=\frac{1}{\sqrt{1-x^2}}\
\frac{d}{dx}(\arctan(x))=\frac{1}{1+x^2}
\end{gather}
Suppose we have:
\begin{gather*}
f(x)=\arcsin{(\arctan{(\arccos{x})})}\
\frac{d}{dx}[f(x)]=\frac{d}{dx}(\arcsin{(\arctan{(\arccos{x})})})\
f'(x)=\frac{1}{\sqrt{1-(\arctan{(\arccos{x})})^2}}(\frac{d}{dx}(\arctan{(\arccos{x})}))\
f'(x)=(\frac{1}{\sqrt{1-(\arctan{(\arccos{x})})^2}}(\frac{1}{1+(\arccos{x})^2}(\frac{d}{dx}(\arccos{x}))))\
f'(x)=(\frac{1}{\sqrt{1-(\arctan{(\arccos{x})})^2}}(\frac{1}{1+(\arccos{x})^2}(\frac{-1}{\sqrt{1-x^2}})))\
f'(x)=\frac{-1}{\sqrt{1-(\arctan{(\arccos{x})})^2}(1+(\arccos{x})^2)\sqrt{1-x^2}}
\end{gather*}
Nefer
This is for my part a, doesn't related but I didnt solve using triangle
pretty tedious, so I am looking for a faster method
Triangle should shorten the calculus route
why want another way
I think 1 +x^2 there can be simplified in a right triangle
Such that a side is x, a side is 1
b) Now, suppose that in a right-angle triangle, we have an angle $\theta$ such that:
\begin{gather*}
\tan{\theta}=\frac{\text{opposite}}{\text{adjacent}}\
\text{(Let opposide side be $x$, while the adjacent side be 1)}\
\text{Hypotenuse =} \sqrt{\text{adjacent}^2+\text{opposite}^2}=\sqrt{x^2+1}
\end{gather*}
Ok i got sth like this
Nefer
What can I do next from here?
$\sin y = \frac{1}{\sqrt{x^2 + 1}} \ \
\dv x \sin y = \dv x \left( \frac{1}{\sqrt{x^2 + 1}} \right) \ \
y' \cos y = -\frac{2x}{\sqrt{(x^2 + 1)^3}} \ \
\cos y = \frac{x}{\sqrt{x^2 + 1}}$
Now i need to find sin theta?
VulcanOne
Then you solve for y' by substituting cos y
oge let me do it
@vital crag thanks btw 
i think doing that gives the cleanest solution. you get f(x) = arccot(x) for positive x and then it's just a standard derivative
b) Now, suppose that in a right-angle triangle, we have an angle $\theta$ such that:
\begin{gather*}
\tan{\theta}=\frac{\text{opposite}}{\text{adjacent}}\
\text{(Let opposite side be $x$, while the adjacent side be 1)}\
\text{Hypotenuse =} \sqrt{\text{adjacent}^2+\text{opposite}^2}=\sqrt{x^2+1}
\end{gather*}
Now, to find $\sin{\theta}$:
\begin{gather*}
\sin\theta=\frac{\text{opposite}}{\text{hypotenuse}}\
\sin \theta = \frac{x}{\sqrt{x^2+1}}
\end{gather*}
Now, we substitute back into the given equation, such that:
\begin{gather*}
g(x)=\arcsin(\frac{1}{\sqrt{1+x^2}})\
g(x)=\arcsin(\sin x)\
\frac{d}{dx}[g(x)]=\frac{d}{dx}(\arcsin(\sin x))\
g'(x)=\frac{1}{\sqrt{1+(\sin x)^2}}(\frac{d}{dx}\sin x)\
g'(x)=\frac{\cos x}{\sqrt{1+(\sin x)^2}}\
\end{gather*}
Nefer
Isn't it the same, i said 1 + x^2 there
ahh
b) Now, suppose that in a right-angle triangle, we have an angle $\theta$ such that:
\begin{gather*}
\tan{\theta}=\frac{\text{opposite}}{\text{adjacent}}\
\text{(Let opposite side be $x$, while the adjacent side be 1)}\
\text{Hypotenuse =} \sqrt{\text{adjacent}^2+\text{opposite}^2}=\sqrt{x^2+1}
\end{gather*}
Now, to find $\sin{\theta}$:
\begin{gather*}
\sin\theta=\frac{\text{opposite}}{\text{hypotenuse}}\
\sin \theta = \frac{1}{\sqrt{x^2+1}}
\end{gather*}
Now, we substitute back into the given equation, such that:
\begin{gather*}
g(x)=\arcsin(\frac{1}{\sqrt{1+x^2}})\
g(x)=\arcsin(\sin x)\
\frac{d}{dx}[g(x)]=\frac{d}{dx}(\arcsin(\sin x))\
g'(x)=\frac{1}{\sqrt{1+(\sin x)^2}}(\frac{d}{dx}\sin x)\
g'(x)=\frac{\cos x}{\sqrt{1+(\sin x)^2}}\
\end{gather*}
Nefer
And "let opposite side be 1, while the adjacent side be x"
I think i made big mistake there, hold up
b) Now, suppose that in a right-angle triangle, we have an angle $\theta$ such that:
\begin{gather*}
\tan{\theta}=\frac{\text{opposite}}{\text{adjacent}}\
\text{(Let opposite side be $1$, while the adjacent side be $x$)}\
\text{So that, we have:} \tan \theta = \frac{1}{x}\implies\theta=\arctan{\frac{1}{x}}\
\text{Hypotenuse =} \sqrt{\text{adjacent}^2+\text{opposite}^2}=\sqrt{x^2+1}
\end{gather*}
Now, to find $\sin{\theta}$:
\begin{gather*}
\sin\theta=\frac{\text{opposite}}{\text{hypotenuse}}\
\sin \theta = \frac{1}{\sqrt{x^2+1}}
\end{gather*}
Now, we substitute back into the given equation, such that:
\begin{gather*}
g(x)=\arcsin(\frac{1}{\sqrt{1+x^2}})\
g(x)=\arcsin(\sin\theta)\
g(x)=\theta\
g(x)=\arctan\frac{1}{x}\
\frac{d}{dx}[g(x)]=\frac{d}{dx}(\arctan\frac{1}{x})\
g'(x)=\frac{1}{1+\frac{1}{x^2}}(\frac{d}{dx}\frac{1}{x})\
g'(x)=\frac{1}{1+\frac{1}{x^2}}(-\frac{1}{x^2})\
g'(x)=\frac{-1}{x^2+1}
\end{gather*}
Nefer
Finally locked in

the derivative is not -1/(1 + x^2) for x < 0
why not?
if sin y = 1/sqrt(x^2 + 1) then you can't just say "oh i drew a triangle so therefore the other side is x and so cos y = x/sqrt(1 + x^2)." we actually have cos y = |x|/sqrt(1 + x^2) in this case
homie its 1am
The triangle does require that x is positive
no
take the side length to be |x|
problem solved
you should try the tan substitution as well
you'll have to do some domain/range work though
derivative of 1/|x| is what guys
i did do that in my work
@rocky tusk @supple mantle Ok final solution
I go to sleep now
Thanks guys
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when you transitioned to the last line you dropped an x
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where did k+1 come from I keep getting k+12
looks like it got cut off there
also, the augmented matrix's closing bracket is missing, which also hints at the text being cut off
oml
good call lmao
thx i thought i was missing smthng
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Why is u taken as 0 in the answersheet to part b? didn't we calculate it to be -3 in part a?
u changes with the time
for a, it's u at time t=0
for b, it's something else
why is it 0 tho?
'initial'
im sorry i dont understand
because we are finding the initial velocity
and initial means t=0
no in question b it asks to calculate the maximum distance upstream
here we are calculating displacement
so idk why u is 0 here
No worries, thank you for trying to help.
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i've done 3a (XY = (-2, 3, 6) and |XY| = 7) but i'm not sure what is being asked for 3b. is it asking for a parallel unit vector?
well how would you get a unit vector?
Its asking for a unit vector, unit vector is a vector with its mod equating to 1 & the required unit vector is supposed to be in same direction as XY vector ( yes , you are right )
what country uses mod? normally we say norm
ah, that would make sense. let me check my notes, because i'm pretty sure it ends up being something like XY divided by |XY|
|| India, by Norm we mean like, 'Norm of vector XY is 7?' ||
Yes, because when you take the norm of that vector that you get by driving XY with its norm, it's new norm should be 1.
i'm not sure what norm means, but it does in fact check out with my notes lol
thanx for the help
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woah, there were messages completely missing on my end. that's weird
What do you mean?
i didn;t see that other users messages at all until i rebooted my app because i knew something was off
Interesting.
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hey guyss, i need help with understanding smth. what on earth are eigen values of a matrix?????
Of order A? dont matrices usually have a number as their order?
sry mb
typo
we basically equate |A-xI|=0
the roots of x here are eigen values
dw abt lmaoo
okay i dont get it... what is the purpose of an eigen value? what to do they do?
A visual understanding of eigenvectors, eigenvalues, and the usefulness of an eigenbasis.
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these values are basically there so that they can be transformed
Eigenvectors and eigenvalues come in pairs.
Eigenvectors are the vectors that, when A acts on them, they stay in the same direction.
Eigenvalues are the stretch factors that A applies to their corresponding eigenvector
okay yeah that
youll probably learn more from this video than anyone here can tell you over text
(its a bad idea to take up too many channels at once)
aaaa alr alr thanks so much!
isn't eigenvalue is just kinda like the dilation factor of the eigenvector
ummm alr so i realised my foundation is super weak. i havent yet learnt them as representation of vectors in class lol
okay so theres a problem that i have thats been bugging me and idk what to do about it lol. lemme see if i can send it
Q 18
i dont think i need to learn what eigen values are to answer this...
okay so
can we break P into 2 matrices such that one of them is an identity matrix? if yes then what type of matrix would the other one be?
... i dont know??? i dont even understand the question
we basically need to find P^5 here. I3 is a 3x3 identity matrix and we are given Q-P^5=I
if You mean that im supposed to break P into the from I + B then im assuming be would have the lower part below the diagonal as 3 9 and 3
exactly
Okay great!
can you verify if the given matrix(B) is nilpotent?
ummmm yes if i sqaure it then im pretty sure we would get 0
(N^2 is not 0 here)
no wait if we sqaure it wed get 9 and if we cube it we would get 0
exactly
yeah yeah mb
do you remember binomial expansions?
yes i do
That would be I + 5B + 10 B^2 +10B^3+5B^4+B^5
exactly
So eveything after B cube is gonna be 0
Okay yayy! ummmm i got that
wait alr alr yeah i think so
do i try it out on my own and come back if i have doubts?
we already found B and B^2 earlier
yea
(well i gtg now, if you do have any other doubts you can ping the helpers by doing <@&286206848099549185> )
okayyy Thanks so much for your help omg
I GOT IT!!! WOOO
Also quick q, how do i know that im supposed to split matrix P as (I+B)?? like ig im trynna find out why we did that
<@&286206848099549185>
can someone help me out
no need to ask for help, just ask your question :)
13k people got pinged because of this single message ๐
lmao alrr
oh shit
could somone help me out with this?
nah he was jus trynna help me out, i just started using dc and this is the my first time on this server so it was pretty helpful
ic
lmfaooo yeah thast valid. dw abt it, thanks anyway
the idea here is that we want to split P into a nilpotent matrix and something else, then when we compute powers of (I + B)^n there will be fewer terms (why?).
we can see ones on the diagonal and we know that I is never nilpotent, so we can subtract P - I and hope that the matrix we get, B, is nilpotent
okay so this isint a fool proof method? we are basically just guessing ??
if you can find a nilpotent matrix in the decomposition, then this is a faster method to solve the question
faster than computing P^5 by hand, anyway
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I did pt.a but idk how to do pt. B
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โ Original question: #help-36 message
@tidal birch did you have something ? Bc Iโm still stuck
I got this but idk, itโs not correct
@late gazelle Has your question been resolved?
Circle
Yea
But idk how to make a circle tilted, so my classmate said to do the above working but idk why it โworksโ
Yea
because the points on the circle are still the same radius away
so they are part of the sphere
Mhm
then what you did is valid
Uh huh, but idk why making x in terms of y and z make it true
Each equation corresponds to one of the two surfaces
if they are both true
then it corresponds to their intersection
so it "selects" all points that are on both surfaces
if you solve their system
Anybody know how to apply the calabi yau manifold?
Open your own help channel and someone will help you
ok, sure
or what did you mean here exactly
Iโm my final line of working
I take the equation of the plane and solve for x
Then sub that into my sphere equations
yes
then you can rewrite the sphere equation to look nicer
but itll still be a circle
yes
x depends on y and z
y and z are your parameters
if x depends on y and z it doesnt add a dimension
Ahh ok
a dimension has to be independent
its basically the number of independent variables
When i first learned about that, i visualized that as once you fix y and z, the value of x is fixed
which means the surface has no space to move on that third axis
It only has โspace to moveโ on the domain of the intersection circle in this case right
Open your own help channel
i guess the circle is a 1d curve tho technically?
its just that y and z have two possibilites for each other
so sorry theres only one parameter
the other one can be different by sign
only
What plane is it talking about, one of the co ordinate plane?