tolong dijawab ya menggunakan cara

K = 2 x phi x r

a. K = 572/7
572/7 = 2 x 22/7 x r
527/7 = 44/7 x r
527 = 44 x r
r = 13

b. K = 7/2
7/2 = 2 x 3.14 x r
3.5 = 2 x 3.14 x r
3.5 = 6.28 x r
r = 0.55

c. K = 88/9
88/9 = 2 x 22/7 x r
88/9 = 44/7 x r
r = 88/9 x 7/44
r = 14/9

d. K = 66
66 = 2 x 22/7 x r
66 = 44/7 x r
r = 66 x 7/44
r = 21/2