Jawabanmu

2014-06-10T20:15:57+07:00
K = π × 2r
k = 22/7 × 28 × 28
k = 22 × 4 × 28 = 2464 cm
2014-06-10T20:17:47+07:00
K= 22/7 x Diameter 
atau 
k= 2x 22/7 x jari"

k= 22/7 x (28x2)
  =22/7 x 56
  =176