#help-19
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the numerator doesn't cancel out tho
make it cancel
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@thorn palm
any trials?
Trials?
What have you tried I mean
All that
ok
Wdym have u done this question before
I solved with at your first ask
the channel you closed
Sorry
Yeah I got that
Idk how much help you want
the idea itself of using pythagoras?
Yeah
or especially the one you wrote?
Basically this proof is from shkwing that distinct two side has same length
Which 2 sides
Yeah so that one
I tried using Pythagoras
To solve for that
Is that a rhetorical question or a real question
part of proof
Like do u want me to do it
Is that triangles angle same as the other triangle ?
do you know coordinate of those two point?
you know the angle
To find coordinates
Do you know that coord of point A=(cosA,sinA)?
Isn’t A an angle
Not yet
Wait what
I’m still getting the red pint as
For x coordinate as
-1 -cosA-B
how so?
Yeah
that is not the x coord
Can you tell me how you got it?
you can do similar thing tk get coord of red&blue point
Very true I know
So you can just get the position of red&blue point
To find x coordinate for red
Do I have to find the actual triangles lengths first ?
you can do with length 1 sides
I think you dont have to think about that triangle
But how can u know any lengths of the small triangle
hypo is 1
.
not actually
😭
Yea
And you can do same thing with blue point
How do u find that angle
which angle?
see what I did for red point
here
no
Yup
That angle where A is but not actually the angle A
Cause it’s 180-A plus that A part
Which is C
you can actually just express that angle with only using B
Oh so just 180-B
yes
yep
So now do we prove
Visually?
I mean the fact itself
Now I know
Where does the minus go
cos(180-A)=-cosA
K
.
you mean $a_h$?
Dri111
Yeah
that is neither orange segment
Uhh yes it is
It’s the hypo
Do I just make ah=
Am I suppose to find another tangle
no we found coord of red & blue point right?
Yeah
and left orange is line connecting red and blue
Have you learn how to calc distance of two point before?
Ok yeah
so you can calc length with red&blue coord
How tf do we simplify that
How do u expand cos b -cos a)^2
$(a-b)^2=a^2-2ab+b^2$
Dri111
you can use this formula
Well I haven’t starting expanding yet
$\sqrt{(1-\cos{(A-B)})^2+(\sin{(A-B)})^2}$
Dri111
you need to put 1 inside square
yes
Do u have the expanded version on u
Is middle one you wrote 2cos(A+B)?
Yes
why?
I don’t know how to expand that one ngl
same $(a-b)^2=a^2-2ab+b^2$
Dri111
in this case a=1 and b=cos(A-B)
btw I recommend writing ${\cos{(A-B)}}^2$ as $\cos^2(A-B)$ not $\cos(A-B)^2$
Dri111
Now the sin part
$(\sin(A-B))^2$ right?
Dri111
Dri111
Ok now we start eliminating ??
yes
Is sinA+B)^2the same as sinA^2 and sinB^2
Or
do you think $(a+b)^2=a^2+b^2$?
Dri111
No
so yeah, not the same
How on earth do I simplify this
and where does sin(A+B)^2 comes from?
Meant to be a-b
do you know the fact that for real number x $\sin^2 x + \cos^2 x =1$?
Dri111
Now I know
is this question from lecture or class?
what are you learning about rn?
Trig
Well this book is like scholarship questions which are extended
And we still are learning trig calc normal version
Simply this book has stuff we haven’t learnt
And it is first time you saw this?
Yeah
both side
wdym?
Idk but I found these
If not can u work ur magic and simplify for me
@thorn palm ?
Dri111
sorry my Internet is not properly working rn
2 I mean
Is it 2 both sides?
yes
they become 1
Does that whole 2 things go away
so yes if I understoood your question correctly
if you mean (cos(A-B))^2 and (sin(A-B))^2 both disappears, then yes
didnt you say 2 on lhs?
Yea mb
The 1-2?
RHS was $1-2\cos(A-B)+\cos^2(A-B)+\sin^2(A-B)$ right?
Dri111
Yeah
and $\cos^2(A-B)+\sin^2(A-B)=1$
Dri111
Yup
So $1-2\cos(A-B)+\cos^2(A-B)+\sin^2(A-B)=1-2\cos(A-B)+1$
Dri111
Yes
therefore RHS is 2-2cos(A-B)
right 2 is multiplied with cos(A-B)
Ok
same as 2-2×3 is not 0
Yes
then now you can eliminate more
Could u finish it off please
you should do it yourself
Yeah
where?
that one is just a steps for showing that rhs should be 2-2cos(A-B)
you should correct this equation eith that
yes
you should fix rhs with 2-2cos(a-b)
because of this
you forgot to write 2 for sinBsinA at LHS
now eliminate
?????
I just brought the 2-2 to the rhs
yes
divide both side by -2
for this just divide by 2
And the divide by 2 on all sides?
yes
about 3~4min
I understand everything but just the simplifying parts I’m iffy about
Well thanks for this super long journey
Thanks for ur time
have a nice day
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||substitution|| ||u = pi - x||
It will expand even more?
Since there would a square of (pi+u)
not gonna lie this is some integration bee level integrals
true
you will see why this eventually works out
whenever you have some weird trig integral with bounds 0 to pi or 0 to pi/2.. something like that
the solution almost always involve a substitution of that type, and this case is not an exception
in fact the denominator (sinx)^4 + (cosx)^4 at the start may tip you off at that
lmao
I am stuck at the same thing now but with more terms to solve 
Yea there must be some sort of trick going around here, which i obviously can't catch
what do you get after substitution?
3 terms
hm nice
so the sum of these three integrals equals the value of the original integral
do you notice anything similar / different about the new integrals you have and the one you have at the bottom of this page?
the next step is to scour through https://en.m.wikipedia.org/wiki/List_of_definite_integrals and pray the answer is there
In mathematics, the definite integral
∫
a
b
f
(
x
)
d
x
{\displaystyle \int _{a}^{b}f(x)\,dx}
is the area of the region in the xy-plane bounded by the graph of ...
entertaining entry lol
🥲😂
the third term is quite similar to the original ques
they get cancelled
right
still 2 terms left...
with the cancellation in mind, can you show me what integral we have to evaluate exactly to get our answer?
@sonic sail Has your question been resolved?
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can someone tell me about steps involved in following factorisation?
thats the steps right
ur confused abt the steps
yes
anything works
why did I get x-2^2
thats my problem aswell
wait u got that as well?
i tried many different ways but i keep on getting something in additon and subtraction
Then the pic must be wrong
use the ,w thing
I think it should help
,w x^3+x^2-16x+20
@formal jasper
that answer is wrong probably
x³ + x² - 16x + 20
= x³ - 2x² + 3x² - 6x - 10x + 20
= x²(x - 2) + 3x(x - 2) - 10(x - 2)
= (x² + 3x - 10)(x - 2)
= (x² - 2x + 5x - 10)(x - 2)
= [x(x - 2)+5(x - 2)](x - 2)
= [(x - 2)(x+5)](x - 2)
= (x - 2)(x + 5)(x - 2).
Thats it
i just saw the question has a negative x^2 thats why i wasnt getting to required equation
the given solution has a positive
well
thanks
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i dont get how thiss equates to 400e^-43 sqrt337
do you know what the dot product is
somewhat
its -2 * -2/sqrt337 + 3*3/sqrt337 ... no?
but thats the answer
337
ok
so it's 337/sqrt(337)
which is just sqrt(337)
so the dot product is just sqrt(337)
oh
so 400 e^-43 * the dot product is just 400 e^-4e sqrt(337)
why is it 337 its some rationlizing thing right
what is it called agfain
as in 337/sqrt337 = sqrt337
there's a thing called rationalisation but this isn't it
it's just division
i guess you could put it like
337 / (337)^0.5 = 337^0.5
power rules
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did you send us a picture of something you've rubbed out
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i keep getting 3y-4
show ur working
i did 9-16y^2 over 3-4y^3/y
i switched the ys cuz they can't be negative
then for the bottom fraction i multiplied 4y^2 by y for common denominator
$$y^{-2} = 1/y^{2}$$
JustToPro
WAIT WHAT
$$9-16y^{-2} = 9 - \frac{16}{y^{2}}$$
JustToPro
OHHHHH
i moved it to the other fractionnnn
wait let me try again
btw i have another qs
how is this not 5
how are u getting 5?
in simplest form that is equal to N\M
simplify the fraction to the simplest form
and then the numerator is equal to N , not before
huh
wait
I STILL GOT 5
bro i knew i should've started studying earlier
i still have like 4 sections
u gotta simplify the fraction before making them equal
but i'm still getting the same answer for this
3y-4
i'll write down my work
wait
i think i got it
when -16 and -4 are cancelled out
are the numbers in the boxes the actual answers?
does the 4 become positive
yea
JustToPro
u cant divide numbers when they are being added or subtracted
$$9y^2 = (3y)^2$$
$$ 16 = 4^2$$
JustToPro
use the identity i sent above
i'm so confused rn
here u cant cancel out 9y^2 with 3y and 16 with 4 , not possible
$$\frac{9y^2 - 16}{3y-4} \neq \frac{9y^2}{3y} - \frac{16}{4} \neq 3y-4$$
THEN I CANCEL THE 2 (3Y-4)
JustToPro
yeah like that
OMGMGMGMMGMGG
THANK YOU SO MUCH
THIS IS THE HAPPIEST MOMENT OF MY LIFE
I OWE YOU MY KIDNEY
.close
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How can I calculate the number of digits of 2010¹⁰?
Is that a formula
sure?
@mystic saffron Has your question been resolved?
Wait, what?
so take like 546
546 is between 100 and 1000
so log_10(546) is between 2 and 3
so if you round up it's 3
which is the number of digits
Yes, but why does this work?
well it's sorta intuitive from the example
i mean let's make it rigorous
if a number has n digits
it is at least 10^(n-1) but less than 10^n
so log of it is between n-1 and n
so if you round it up, it's n
If you can prove that $\sum_{i = 0}^k a_i \cdot 10^{i-k}$ is inferior to 10 then you've got yourself the formula
for 0<a_i <10 of course
because : $n = \sum_{i = 0}^k a_i \cdot 10^i
\ \log_{10}(n) = \log_{10}(\sum_{i = 0}^k a_i \cdot 10^i) = \log(10^k(\sum_{i = 0}^k a_i \cdot 10^{i-k})) = \log(10^k)+\log(\sum_{i = 0}^k a_i \cdot 10^{i-k})=k+\log(\sum_{i = 0}^k a_i \cdot 10^{i-k})$
Azenx
where k+1 is the number of digits
Azenx
Btw to prove that the "reminder" is smaller than 10 and is positive you can just compute it for its max and min value
$\sum_{i = 0}^k 9 \cdot 10^{i-k}$
Azenx
And $\sum_{i = 0}^k 10^{i-k}$
Azenx
These two are power sums so you should be able to compute them
and you've proved the formula
Some work to do for the rest of the day... 😆 Thanks
@mystic saffron Has your question been resolved?
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x+1/x+2 < 1
Helpp!!
Anyoneee??
!show
Show your work, and if possible, explain where you are stuck.
lol kk
show what you’ve done so far
Why soo stubborn
I jsut asked for help
What is this server for anyways
If u aren;t gonna help me?
!show
Show your work, and if possible, explain where you are stuck.
Where exactly are you stuck?
We are trying to help, but show us how far you've gotten on your own
Also do you mean (x-1)/(x+2) < 1?
Make sure you parenthesize the numerators and denominators to avoid confusion
this is not a free answers server
it's help
not 'do my work for me'
what have you tried?
- it's human who takes time to help u. You won't instantly get a response
!volunteers
Helpers are just people volunteering their time to help you. Be polite and patient.
Yhh
OK, that's a little different. Your thoughts?
Remember, with an inequality, multiplication can change the direction of the sign
Correct. Also be sure to consider the special case where the denominator is 0 so you don't lose a possible switchover
Quadratic Equation?
No, (x-1)/(x+2) has a 0 denominator when x = -2, just consider that one of your critical points
0 as denominator??
Because it means the function approaches an asymptote and may change sign
Actually have you tried graphing (x-1)/(x+2)?
We haven't started graphical in skl
Right, but just on paper or something
One sec
kk
k
Does that help?
Exactly what am I supposed to do?
Well, where is that graph < 1 and where it is bigger than 1 and why?
With that
Use that graph to help you see and then use the equation to get the exact answer
Can I say smth
Sure
We aren;t supposed to use graph
Done that alr
What did you get?
But when I put = 0 doesn;t that make it a quadratic equation?
Not at all
Bruh
The weird thing is that when u're doing the equation u find that the x delete themself
I have to be going, sorry, I'm hoping @heady raptor can help more
Leave it to me !
If x,y are real numbers and if $y = \frac{x - 2}{x + 1}$ , then $y(x + 1) = x - 2 \implies y(x + 1) + 2 = x$
Watynecc
Yh
let me cook something
I thought of that
kk
u done?
The funny thing is that the answer is x > -2
I just need the workings
u there @heady raptor
There's 2 solution right ?
How u could if I got this while
maybe check the limit of (x-1)/(x+2) ?
kk
Not sure
It's less than not less than or equal to
Oh my bad
Not sure we supposed to use graph
np
yeah... but at least we have some clues
yhh
Still don't work
Bruh
maybe we don't need to find x ?
Idk at this point just confused
(x-1)/(x+2) < 1 <=> 0 < 3 which is true ?
Yeah me too ;-; I hate fraction just for this shit
Exactly
I bet it's a missinput from the teacher ;d
Or else there's no x and we done with this
Alr I'm out i'm going to pray I hope I helped you ;-;
Take note for next class maybe it would be precious at the exam
It from a text book lol
Am gonna drag for bonus mark lol
Oh.
hey ! ;-;
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How would I be able to differentiate this?
.close
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you need to choose u such that its derivative is already there
so what can you pick that has a derivative you can already see?
what is the derivative of ln(x)?
yep! and look at that, it's already there :)
so choose u = ln(x)
ofc!! hopefully that helps
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@tiny brook Has your question been resolved?
@tiny brook Has your question been resolved?
@tiny brook Has your question been resolved?
hello @tiny brook yes we need to evaluate ln|ln(x)| between x=e and x=6
so we get ln|ln(6)| - ln|ln(e)| = ln(ln(6))
yes it should be OK
@tiny brook Has your question been resolved?
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Is the solution correct?
I don't know a website to check for a curve
yea all 3 are right
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for question d. g'(4) would be the original function at x = 4 which is -2?
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how do i do 1c and 1d?
from the first row you get, c2=-c1-2c4. repeat this for each row and try to replace where possible everything with just the pivot columns, c1, c3, c5, c7
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how do u do this
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is pearson's coeffecient same or similar to the r from a linear regression?
@open elbow Has your question been resolved?
<@&286206848099549185>
hm?
is pearson's correlation coeffecient same or similar to the r from a linear regression?
Pearson correlation measures the strength and direction between two numeric variables while simple linear regression describes the linear relationship between a response variable and an explanatory variable
they are the same thing usually
like if you have a calculator that performs a linear regression and outputs a variable called 'r' or 'correlation' that's most likely pearson's coefficient
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ok so
if 2 lines are perpendicular to each other their slopes must be reciprocals of each other
you can use this and point slope form to create the equation for the line, then draw it
if you are done with this type “.close”
which is?
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what do you mean by this
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I'm doing the Bolzano-Weierstrass theorem, but I didn't understand one thing: I know that A<an<B, by doing the proof I obtained 2 sequences Ak and Bk which tend to 2 limits. I didn't understand how the limit of the difference (B-A)/2^k which tends to 0 leads me to say that the two limits of Ak and Bk are equal.
@tired obsidian Has your question been resolved?
<@&286206848099549185>
show the entire proof you're referencing
\textbf{Bolzano-Weierstrass Theorem}: Given a bounded sequence ${a_n}$, there exists at least one convergent subsequence.
\textbf{Proof}: Let's assume the sequence ${a_n}$ is bounded, meaning there exist constants $A$ and $B$ such that $A \leq a_n \leq B$ for all $n$ in the natural numbers.
We divide the interval $[A,B]$ by its midpoint $C = \frac{A + B}{2}$, creating two intervals: $[A,C]$ and $[C,B]$. At least one of these intervals contains infinitely many terms of the sequence ${a_n}$. In other words, either the set ${n \in \mathbb{N} : a_n \in [A,C]}$ or ${n \in \mathbb{N} : a_n \in [C,B]}$ is infinite.
Suppose, without loss of generality, that $[A,C]$ contains infinitely many terms, denoted by $[A_1, B_1]$, where $A \leq A_1$ and $B_1 \leq B$. This interval satisfies $B_1 - A_1 = \frac{B - A}{2}$.
We repeat this process with $[A_1, B_1]$, dividing it into two intervals $[A_2, B_2]$ and $[A_1, C_1]$, where $C_1 = \frac{A_1 + B_1}{2}$. Again, at least one of these intervals contains infinitely many terms of ${a_n}$.
Continuing this iterative process, we obtain sequences $A_k$ and $B_k$ such that:
\begin{itemize}
\item $A \leq A_k \leq A_{k+1} < B_{k+1} \leq B_k \leq B$, for $k$ in the natural numbers.
\item $B_k - A_k = \frac{B - A}{2^k}$, for $k$ in the natural numbers.
\end{itemize}
Moreover, the interval $[A_k, B_k]$ contains infinitely many terms of the sequence ${a_n}$ for all $k$ in the natural numbers.
This process guarantees the existence of a convergent subsequence of ${a_n}$.
alee
In particular, the interval $[A_1,B_1]$ contains elements of the sequence $a_n$, thus there exists the first integer $n_1$ such that $a_{n_1} \in [A_1,B_1]$. Similarly, there exists a first integer $n_2$ greater than $n_1$ such that $a_{n_2} \in [A_2,B_2]$. By iterating this process, for $k = 1, 2$ and extending it to $k = 3, 4, 5, \ldots$, we establish a strictly increasing sequence of integers:
[ n_1 < n_2 < n_3 < \ldots < n_k < n_{k+1} < \ldots ]
such that $a_k \in [A_k,B_k]$ for every $k \in \mathbb{N}$.
Since $B_k - A_k = \frac{B-A}{2^k}$, we have:
[ A_k \leq a_{n_k} \leq B_k = A_k + \frac{B-A}{2^k} \quad \text{for } k \in \mathbb{N} ]
From equation (34.9), the sequence $A_k$ (and also $B_k$) is monotonic and bounded. By the theorem on monotonic sequences, $A_k$ admits a finite limit as $k \rightarrow +\infty$. Let's denote this limit as $\iota \in \mathbb{R}$.
Considering that $\frac{B-A}{2^k} \rightarrow 0$ as $k \rightarrow +\infty$, both the first and the last terms of equation (34.12) converge to $\iota$ as $k \rightarrow +\infty$. Therefore, by the Carabinieri theorem, we conclude:
[ \lim_{k \rightarrow +\infty} a_{n_k} = \iota ]
This expression represents the limit of the subsequence $a_{n_k}$ as $k$ tends to infinity.
alee
@quasi sparrow
B and A are fixed, and the denominator grows as 2^k so the fraction goes to zero
$A_k$ tends to $A_{\infty}$. $B_{k}$ tends to $B_{\infty}$. How are $A_{\infty}$ and $B_{\infty}$ related to each other?
alee
they don't relate and you don't need to know
alee
$$ |B_{\infty} - A_{\infty}| \le |B_k - A_k|. $$
alee
Apply squeeze theorem:
$$ |B_{\infty} - A_{\infty} | \le \lim_{n\to\infty} |B_k - A_k| = 0.$$
alee

$$B_\infty \lim_{n\to\infty} B_n = \lim_{n\to\infty} (B_n-A_n) + \lim_{n\to\infty} A_n = \lim_{n\to\infty} A_n = A_\infty$$
alee
Why does this matter
you only need to know $\lim_{k \to \y} A_k = \iota$
riemann
bc i use it
$$ |B_{\infty} - A_{\infty} | \le \lim_{n\to\infty} |B_k - A_k| = 0.$$
alee
here
oh you're being confusing by a making new variable for one that already existed
yes they're equal
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i know i can use (a + b)^2 = a^2 + 2ab + b^2
but how would i distribute it the long way
i end up with 25 + 1v4
does the 5 make it 5v2?
wait is the problem (sqrt(2) + 5)^2
yes
well so distributing it the long way would work like this
sqrt(2)*sqrt(2) + sqrt(2)*5 + 5sqrt(2) * 55
wait im actualyl slow
i think ive done too much math today and need a break
i wasnt multiplying my 5's with my** 1**v2
square root
ok
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Hello I've been working on understanding compactness for a couple weeks now and I just can't seem to tie it all together. Ive been using baby rudin and many yt videos, but i cant connect the idea to continuous, compact maps on R are uniformly continuous. anyone have any tips for the intuition behind this?
I knows theres a lot deeper concepts that play into what compactness is really meant to do, like discrete + compact -> finiteness, but i dont want to go into the rabbit hole of discrete math
what's the question, more specifically?
how do you think of compactness
what is the intuition behind it
what does satisfying compactness mean to you
are we talking open cover definition?
either the open cover or sequential one
sequential one is less intuitive imo
yeah but that doesnt tell you anything about anything
It basically generalizes the notion of closed and bounded to general topological spaces
Any possible way that you cover the space with open sets you can choose finitely many of them and still cover the space
I found the sequential one easier to imagine but the cover one is more useful
The kicker is that it has to be for any possible covering
I think it’s kind of hard to intuit without just working through a bunch of proofs about it tbh
Which is a kinda disappointing answer I suppose
i know what compactness is, Ive been studying it for two weeks now, I just want to connect it to everything else ik
should i learn more about connectedness
first
Did you ever see the morphocular video on it?
honestly if you can convince yourself inverse image of an open set is open for a continuous function what you said plops out, i think
yes
I remember this helping me a bit
i went through this process 2 days ago
combine this fact with compactness definition with open covers
Ive been looking at that recently, but I need to go over inverse images
its not so painful a proof
its really just element chasing
and using a couple balls
Oof but that’s the definition of continuity
yeahi dont know enough about images yet
At least in the gigachad world of topology
yes
so you can use the definition
first answer here made sense to me
maybe you too
I am in a stupid graduate analysis class so i'm having to do a lot of review
just scrolling through the wikipedia definition, it looks like something ive studied but with another name but idk
this was a good answer
see if you can disassemble what you want to show into a bunch of lemmas and a theorem
then work through them
just keep breaking stuff down until you reach something that seems elementary to you and then stop
Is it really more efficient to just go into proofs without feeling fully confident in the idea?
You probably won’t feel confident without proving it
IDK i can only speak for myself that sometimes there isnt intuition to be had prior to convincing yourself
So I guess it could be a chicken and egg issue
sometimes things have a nice conceptual framework that you can work from
But I would just dive into trying to prove lemmas for yourself
other times the framework is mostly that its aligned with a series of consequences
thats why i say this
I’ve always found that my experience in analysis was a lot of definition chasing
ill probably just try to prove things and it might come easier
ye
Just directly restating all the definitions makes it sorta easy
you just need to be honest with yourself
start reading the proof of the thing you want to understand
if they say something you dont believe then you have work to do
At least at first, measure theory was a different beast. Just have to come up with some whack sets out of thin air for that one
i say all this bc i went through heine borel as a person who barely passed real analysis on thursday 
it took like 12 square feet of whiteboard space
Heine Borel theorem is kinda the motivation behind compactness in some sense
It allows you to expand the notion of closed and bounded sets to topological spaces in general
self studying this all is slow
its a benefit, not a curse
you have time to build as strong of a foundation as youd like
at least ill have a strong basis
yeah
ill work through the image things thanks guys
.close
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What is the area between the sine and cosine waves between the interval pi/4 and 5*pi/4? (The purple area is what I need to find the area of.
I just don't know where to begin.
Just to make sure: The signed area or the geometric area?
The geometric area.
also what sine and cosine waves are they. Can you share both functions
They're just normal sine and cosine waves. Nothing special about them.