Jawabanmu

2014-03-25T22:10:38+07:00
L = π.r²
1386 = 22/7.r²
r² = 1386.7/22
r² = 63.7
r² = 441
r = 21cm

jadi Diameter = 42cm

semoga membantu:)
2014-03-25T22:25:42+07:00
L = 22/7.r2 1386 = 22/7.r2 r2 = 441 r = 21 Jadi, jari -jari = 21 cm