Jawabanmu

2014-06-03T19:33:00+07:00
K = keliling
TT = phi
d = diameter
Rumus : K = TT x d
31,4 = 3,14 x d
31,4 : 3,14 = d
10 = d
diameter itu kan 2kalinya jari-jari jadi diameter dibagi 2 => 10:2 = 5
jari-jari = 5
2014-06-03T19:43:22+07:00
K.lingkaran =  \pi × diameter
31,4 = 3,14 × d
d = 31,4 ÷ 3,14
d = 10
2r = d
2r = 10
r = 10 ÷ 2
r = 5