A circle can be cut into smaller and smaller slices and rearranged in the shape of a parallelogram as shown.

The formula for finding the area, A, of a parallelogram with base b and height h is shown.

Which equation represents the area of a circle in terms of its circumference?
A.
a=r2(1/2c)
B.
a=r (1/2c)
C.
a=2cr
D.
a= r (1/4c)