Jawabanmu

2014-02-02T13:32:21+07:00
A. 72/360 . 2 . 3,14 . 20 = 25,12 cm
b. 72/360 . 3,14 . 20 .20 = 251,2 cm²
2014-02-02T14:48:12+07:00
A. p.busur = 3,14*40*72/360
               = 25,12
b. L juring = 3,14*20*20*72/360
               = 251,2