diketahui AOB=72° dan panjang OA=21cm maka luas juring AOB adalah?

dik : Sudut pusat AOB = 72°
r = 21 cm
Luas lingkaran = πr²
= 22/7 × 21 × 21 = 66 × 21 = 1386 cm²
dit: L juring
jawab : L juring = n/360° × Luas lingkaran
= 72/360 × 1386
= 1/5 × 1386 = 277,2 cm²

Luas juring AOB = 72°/360° x L. Lingkaran
= 1/5 x 22/7 x (21cm)^2
= 1386 cm^2/5
=277,2 cm^2