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 …

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 13, 2017 · 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 …

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 …

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 + …

Jul 26, 2024 · 2 I am learning about approximating the area of circle ($\pi r^2$) by the area of polygons ($\frac {1} {2}$ of number of sides * the distance between side and center * length of …

Jan 5, 2014 · 2 I am trying to calculate the area of a specific region inside a circle. The region, in this case, is the green area inside the circle. The given material is the equation, radius and the …

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?

Sep 9, 2016 · Decompose your intersection area into polygons which are completely inside the circle, and circular segments formed by a chord and a part of the arc. Use e.g. the shoelace …