Jawabanmu

2016-05-27T20:42:20+07:00
Cari keliling segitiga
K = 9+12+15
K = 36 cm

Cari jari-jari dengan rumus :
r² = ((K-a)(K-b)(K-c))/(K)
r² = ((36-9)(36-12)(36-15))/36
r² = (27.24.21)/36
r = √(13608/36)
r = √378
r = 19√17 cm