Jika diketahui keliling lingkaran 88cm tentukan luas lingkaran tersebut

K = 2πr = 88
2×22/7×r = 88 = 44/7×r
r = 7/44 × 88 = 14 cm

L = πr² = 22/7 × 14 × 14 = 616 cm²

r = K : 2π ⬅ RUMUS
r = 88 : 2 × 22/7
r = 88 : 44/7
r = 88 × 7/44
r = 2 × 7
r = 14 cm

L = π.r²
L = 22/7 × 14 × 14
L = 308 × 2
L = 616 cm² ✔