keliling suatu lingkaran 66 cm, jika pi: 22/7, maka luasnya adalah...cm²

keliling lingkaran = 2 x phi x r
66 = 2 x 22/7 x r
66 = 44/7 X r
r = 66 : 44/7 = 10,5

Maka, luasnya
L = phi x r x r
L = 22/7 x 10,5 x 10,5
L =346,5 cm2

K = 2πr
66 = 2(22/7).r
66 = (44/7).r
r = 66÷(44/7)
r = 66x7/44
r = 21/2

luas = π.r²
luas = (22/7).(21/2)²
luas = (22.21.21)/(7.4)
luas = (33 x 21)/2
luas = 693/2
luas = 346, 5 cm²