Hitunglah keliling lingkaran yang berjari jari : A. 20 cm B. 30 cm C. 14 cm D. 28 cm Caranya..

A. r = 20 cm
K = 2 x π x r
K = 2 x 3,14 x 20 cm
K = 125,6 cm

B. r = 30 cm
K = 2 x π x r
K = 2 x 3,14 x 30 cm
K = 188,4 cm

C. r = 14 cm
K = 2 x π x r
K = 2 x 22/7 x 14 cm
K = 88 cm

D. r = 28 cm
K = 2 x π x r
K = 2 x 22/7 x 28 cm
K = 176 cm