d = 42 cm tentukan luas lingkarannya???

r = d/2
= 42 / 2 = 21

L = phi × r^2
= 22 / 7 × 21 × 21
= 22 × 3 × 21
= 66 × 21 = 1.386 cm^2

r = 1/2 d = 1/2 . 42 = 21
L = πr" = 22/7 . (21) . (21) = 1386