To solve for the length of the frame, we are actually solving for the circumference of the circle. Circumference is the measure of the length around edge of the circle. It is given by the formula C=2πr, where r is the radius.

D = 20 in r = D/2 = 20 in/2 = 10 in C = 2π(10 in) = 20π in ≈ 62.83 in