jika panjang diameter lingkaran 42 cm. berapakah luas dan kelilingnya ?

d = 42 cm
r = 42 cm : 2 = 21 cm

K = phi × d
K = 22/7 × 42 cm
K = 132 cm

L = phi × r × r
L = 22/7 × 21 cm × 21 cm
L = 1386 cm²

Semoga membantu ya （＾ｖ＾）（＾ｖ＾）

Luas = 1/4x phi x D^2

L = 1/4 × 22/7 × 42 × 42

L = 1/4 × 22× 6 × 42

L = 1/2 × 11 × 6 × 42

L = 11 × 3 × 42

L = 1386 cm2

Keliling = phi × D

K = 22/7 × 42

K = 22 × 6

K = 132 cm