Jawabanmu

2014-01-15T01:09:58+07:00
30 menit = 1,099 km = 1099 m
250x = 250 keliling = 250 . 2 phi r
phi r = 1099/500
r = 2,198 x 3,14 = 6,9-an, tapi prefer ke 7m lah :)
2 5 2