Jawabanmu

2014-06-17T09:35:24+07:00
2014-06-17T09:59:51+07:00
L.juring=a/360×πr²
=1/9×3,14×1600
=314×16/9
=558,22cm²

p.busur=a/360×2πr
28=40/360×2×22/7×r
28=1/9×44/7×r
28×9×7/44=r
40,09....=r
40cm=r