Why is the area of the circle $πr^2$?
98971
Why is $\pi r^2$ the surface of a circle
101339
Area of a cyclic polygon maximum when it is a regular polygon
126799
Calculating the area of a polygon with equal sides inscribed in a circle with radius r.
128274
Why sphere minimizes surface area for a given volume?
90574
How can area be a vector?
6151
Evaluating $\int_a^b \frac12 r^2\ \mathrm d\theta$ to find the area of an ellipse
7134
Confusion related to calculation of pi
150491
Surface area of ellipsoid
148233
Proof that every circle has the ratio of $\pi$
5679
Why is $2\pi i \neq 0?$
79983
Finding the exact area of a circle?
78114
Why is the radius of curvature = 1/(curvature)?
157477
Area of a quadrilateral proof
99714
Expected area of the intersection of of triangles made up random points inside a circle, all the triangles must contain the origin
130686
How is $3\pi-10$ element of $[-\pi/2,\pi/2]$?
65300
Why is $\pi$ irrational?
24419
Why area of a triangle is negative based on naming order?