sebuah keliling lingkaran dengan luas 154 cm

L = π x r²
22/7 x r² = 154
r² = 154 x 7 : 22
r² = 7 x 7
r² = 49
r = √49
r = 7 cm

K = 2πr
K = 2 x 22/7 x 7
K = 2 x 22
K = 44 cm

Luas = phi x r
154 cm = 22/7 x r
r = 154 x 22/7
= √49
= 7

Maka kelilingnya
= 2 x phi x r
= 2 x 22/7 × 7
= 2 x 22
= 44 cm