Jawabanmu

2014-06-04T22:03:26+07:00
7 . caranya cari luas p.panjang dulu lalu dikurangi luas daerah arsiran.
22.5x20=450
450-296=154
luaso=πxrxr
154. =22/7 x r x r
154 x 7/22 = r kuadrat
49. = r kuadrat
7. = r
2014-06-04T22:56:13+07:00
249=(P*L)-(π*r^2)
296=(20*22.5) - (22/7*r^2)
296= 450-(22/7*r^2)
22/7*r^2 = 450-296
22/7*r^2 = 154
22*r^2 = 154*7
22*r^2 = 1078
r^2=1078/22
r^2 = 49
r = √49
r = 7