Jul 28, 2014 · 48 I was looking for proofs using Calculus for the area of a circle and come across this one $$\int 2 \pi r \, dr = 2\pi \frac {r^2} {2} = \pi r^2$$ and it struck me as being particularly …

Feb 12, 2020 · HINT.-In the attached figure you can calculate the intersection point $P$ and the angles $a$ and $b$. You know the area of a circular sector $OPR$ is given by $\dfrac …

Jun 19, 2016 · The circumference of a sphere (measured along the arc) is $2 \pi r,$ so then the surface area of a sphere should be $\pi (\pi r)^2 = \pi^3 r^2$ (here, the radius of the circle is …

What would you set the limits if you need to calculate the area of an infinitesimal ring in cartesian coordinates i.e. $\int dx \int dy $.. where you only want to integrate on the infinitesimal ring..

Apr 29, 2011 · the diameters differ by 9cm, so if the inner circle has radius r, the outer circle has radius r + 4.5. The area of the crescent is the difference in the areas of the circles: pi (r + …

Suppose you have 2 circles that intersect each other in such a way that each circle passes through the other's center. What is the area between the circle (or common area) i.e. area …

4 There's a classic trick to do this with just elementary geometry: The green region is a triangle, and the shaded region is a circular wedge: both have standard formulas for their area. To find …

Jan 10, 2012 · I have two circles, like this: I know the radii of the circles, and I know the X + Y of the center of both circles. Can I get the size of the area that is black in my picture?

Aug 26, 2020 · Does this answer your question? Calculating the area of a polygon with equal sides inscribed in a circle with radius r.

I know how to integrate and deduce the area of a circle using vertical "slices" (dx). However, I wanted to know how to solve the problem another way: slicing the circle like one would slice a …