how do you find are of a circle
Circle As proved by Archimedes, in his Measurement of a Circle, the area enclosed by a circle is equal to that of a triangle whose base has the length of the circle's circumference and whose height equals the circle's radius,[7] which comes to Ï€ multiplied by the radius squared:
Great-circle distance The Earth is nearly spherical (see Earth radius), so great-circle distance formulas give the distance between points on the surface of the Earth correct to within about 0.5%.[1] (See Arc length § Arcs of great circles on the Earth.)