Find the area of each side, first off, do you know how to find the area of a trapezoid
Parallel lines don't exist in elliptical geometry because elliptic geometry, a special case of Riemannian Geometry, is a non Euclidean geometry, in which, given a line L and a point P outside L, there exists no parallel lines because all the elliptical lines intersect.
From the graph it seems to be around the area of 10%.
So,
18,000 * 0.10 = $1,800
Three. Reflection, Rotation, and Point