The first one is C = 2 pi r or C = pi * d d = 8.4 C = 8.4* pi D answer <<<<<<
The second one I got the same answer you did. Just to confirm C = 2 pi r C = 2 pi r / 4 to get 1/4 of the circumference. C = 1/2 pi r
Now you take that away from the entire circle C_3/4 = 2 pi r -1/2 pi r C_3/4 = 3/2 pi r Since r is 6 put it in for r C_3/4 = 3/2 pi * 6 C_3/4 = 9 pi Note you may not have done it the same way. No matter. B <<<< answer
