Jawabanmu

2014-06-10T09:47:07+07:00
L =  \pi x r²
1386 = 22/7 x r²
r² = 22/7 x 1386
r² = 4356
r = √4356
r = 66

diameter = 2 x r
              = 132 cm

semoga membantu :)

2014-06-10T14:15:46+07:00
L=1.386
Ωr2=1.386
22/7*r2=1.386
r2=22/7*1.386
r2=7/22*1386
r2=441
r=√441
r=21
D=2*r=2*21=42