pake cara yg lengkap

r = 20 cm
luas = π r kuadrat
= 3,14 × 20 × 20
= 3,14 × 400
= 1.256 cm2

dik = r = 20 cm
dit = L lingkaran = ....?
jwb = L = π r²
L = 3,14 × 20 × 20
L = 3,14 × 400
L = 1256 cm²