luas lingkaran yg keliling nya 12,56 cm,dengan phi =3,14 aealah

keliling = 2× π × r
12,56 cm = 2 × 3,14 × r
12,56 cm = 6,28 × r
r = 12,56 cm ÷ 6,28 = 2 cm

luas lingkaran
= πr²
= 3,14 × 2cm × 2cm
= 12,56 cm²