rini mempunyai compact disc berdiameter 14 cm brp luas permukaan cd trsbut?

22/7 x 7 x 7 = 154 cm

Luas lingkaran = phi ( 3, 14 atau 22/7 ) ×
r × r ( r = jari - jari )
r = 14 ÷ 2 = 7
= 22/7 × ( 7 ×7 )
= 22 × 49
= 1.078 ÷ 7
= 154 cm 2 ( persegi )