tolong dijawab ya menggunakan cara

1).
a. k = 22/7 x 28 x 2 = 176 cm
b. k = 22/7 x 7 x 2 = 44 cm
c. k = 3,14 x 6,5 x 2 = 40,82,cm
d. k = 3,14 x 18,84 x 2 = 118,3152 cm

2).
a. r = 572/7 x (22/7 x 2) = 13 cm
b. r = 7/2 x (3,14 x 2) = 0,55 cm
c. r = 88/9 x (3,14 x 2) = 1,55 cm
d. r = 66 x (22/7 x 2) = 10,5 cm