Hitung luas dan keliling lingkaran Jika diketahui jari jari 28 cm

Luas = phi . r²
         = 22/7 . 28 . 28
         = 22 . 4 . 28
         = 2.464 cm²

Keliling = 2 . phi . r
             = 2 . 22/7 . 28
             = 2 . 22 . 4
             = 176 cm

L = πr² = 22/7. 28² = 22/7.784 = 17248/7 = 2464 cm²

K = 2πr = 2.22/7.28 = 44/7.28 = 1232/7 = 176 cm