Jon wants to put a circular decorative glass in a table. he cuts a hole in the table that is 20in in diameter. he uses a thin metal frame along the edge of the hole. what is the length of the frame?

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

The metal frame is about 62.83 inches long. 

Main idea on left, details on right