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6 votes
2 answers
999 views

Applications of integrals of rational functions of sine and cosine

I earlier asked this question about conformal equivalence of flat tori with embedded tori. In the ensuing thread the integral $\displaystyle\int\frac{dx}{R+\cos x}$ occurred. If I'm not mistaken, it ...
Michael Hardy's user avatar
6 votes
1 answer
2k views

Volume vs. Surface Area Integrals

In order to find the volume of a sphere radiud $R$, one way is to slice it up into a stack of thin, concentric disks, perpendicular to the $z$-axis. a disk at any point $z$ will have radius $r=\sqrt{R^...
Dylan's user avatar
  • 16.6k
4 votes
1 answer
387 views

I've never been so confused (Application of Integral Calculus)

Here's a problem on Application of Integral calculus to find the work done in moving a particle. I was able to 'reach' the 'right answer'. But I'm totally confused and utterly dissatisfied with the ...
Abhishek A Udupa's user avatar
3 votes
2 answers
295 views

Can we clarify this "accumulated money flow" application of integration?

I read about this model/application in Calculus with Applications, 11th Edition by Lial, Greenwell, and Ritchey (example), where if you have a function $f(t)$ that models some revenue stream, the rate ...
Mike Pierce's user avatar
3 votes
5 answers
110 views

Finding the area bounded by $y = 2 {x} - {x}^2 $ and straight line $ y = - {x}$

$$ y =\ 2\ {x} - {x}^2 $$ $$ y =\ -{x} $$ According to me , the area $$ \int_{0}^{2}{2x\ -\ { x} ^2}\, dx \ + \int_{2}^{3}{\ {x} ^2\ -\ 2{x} }\, dx \\ $$ Which gives the area $ \frac{8}{3}$ But ...
user avatar
3 votes
1 answer
183 views

How to get the integral of $\log(\det(A + Bt))$ w.r.t variable t?

Suppose we have two positive definite matrices $A$ and $B$, now I want to get the integral of: \begin{align} \int_{a}^{b} \log(\det(A + Bt)) dt ~~~~~~~~~~~~\text{for } a, b > 0 \end{align} ...
0o0o0o0's user avatar
  • 123
3 votes
1 answer
320 views

Applied calculus problem

This has been returned as homework and I have to make corrections. My teacher isn't very helpful and I can't afford a tutor. When satellites circle closely around a planet or moon, the gravitational ...
lias's user avatar
  • 200
3 votes
1 answer
400 views

Domains of Integration -- the kernel trick and box-muller

I wonder if there is any deeper connection between two "tricks" from applied math, the kernel trick and the box-muller algorithm for generating draws from a random normal. The kernel trick, used in ...
isomorphismes's user avatar
2 votes
2 answers
2k views

Line $y = mx$ through the origin that divides the area between the parabola $y = x-x^2$ and the x axis into two equal regions.

There is a line $y = mx$ through the origin that divides the area between the parabola $y = x-x^2$ and the x axis into two equal regions. Find m. My solution: When I compute my answer, I get $1-\frac{...
bru1987's user avatar
  • 1,927
2 votes
2 answers
282 views

Find the area bounded by $x=-y^2$ and $y=x+2$.

Question Find the area bounded by $x=-y^2$ and $y=x+2$. My Attempt I know it is a very simple question to ask on MSE, but I don't know why I get stuck. If you trace the graph, then the point of ...
NewBornMATH's user avatar
2 votes
1 answer
4k views

Area bounded by$ y^2=x^2(1-x^2)$

Find the area bounded by $y^2=x^2(1-x^2)$? I think in this way as the graph lies between -1 to 1 the area is 4 times of $\int x \sqrt{1-x^2} dx$ limits from 0 to 1. Am I correct?
sai saandeep's user avatar
  • 1,144
2 votes
4 answers
1k views

How does Volume work with integration?

Using a cross section suppose, as described here: Area formula Paul Notes Suppose this is: $y = f(x)$. He says the volume is: $$\int_{a}^{b} A(x) dx$$ But how does area over that interval give ...
Amad27's user avatar
  • 11.2k
2 votes
2 answers
225 views

Volume of a circle $x^2 +y^2 \leq 1$ which is revolving around a line $x+y=2$.

I want to compute the volume of a circle $x^2 +y^2 \leq 1$ which is revolving around a line $x+y=2$. Usually I solved problems about solids revolving around axis and non axis horizontal and vertical ...
Sajib Iglesias's user avatar
2 votes
2 answers
106 views

Find the exact length of the parametric curve(Not sure what I'm doing wrong)

As the title says, I'm not sure what I'm doing wrong. Any help would be greatly appreciated. Here's the problem with my solution. Find the exact length of the parametric curve $(x,y)=(\theta+\...
Timmy Wick's user avatar
2 votes
0 answers
111 views

Application of integrating $\cos^4 x$?

A student asked a colleague the other day for a practical application that involved needing to integrate the fourth power of cosine, but no one here could think of one off-hand other than some volume ...
Ms. H.'s user avatar
  • 21

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