In the figure above, EF is a diameter of the circle with center O and is perpendicular at each end to the trapezoid ABCD. If the area of the circle is , the length of AD is 20 and the length of BC is 10, what is the area of the ABCD?
In the figure above, EF is a diameter of the circle with center O and is perpendicular at each end to the trapezoid ABCD. If the area of the circle is , the length of AD is 20 and the length of BC is 10, what is the area of the ABCD?