Jawabanmu

2014-06-03T14:35:16+07:00
K= 30cm
K= 2.phi.r
30= 2 x 3,14 x r
30= 6,28 x r
r = 30/6,28
r= 4,7.
Jadi, L = phi.r2
= 3,14 . 4,7 . 4,7
= 3,14 . 22,09
= 69,3626 cm2.
2014-06-03T14:56:39+07:00
2.3,14.r = 30
6,28.r = 30
r = 30/6,28
r= 4,7

luas lingkaran = 3,14 . 4,7 .4,7 = 69,3626