Theorem 5.5a: The area of a {n/k} star is
proof 2: Since we know from Theorem 4.3 that the distance from O to P1 is rcos(180k/n)sec(180/n), we could use Corollary 5.1b to get the area of the triangle to be
The summation term is the sum of the triangles and quadrilaterals from Theorem 5.4a.