sebuah lingkaran L=1,54 dm² yg ditanya d=…cm

L = 1/4πd^2
154= 1/4 × 22/7×d^2
196 = d^2
13 = d

1,54 dm2 = 154 cm
r2 = luas / π
= 154 / 22/7
= 154 × 7/22
= 49 cm
r = √ 49 = 7 cm
d = 7 × 2 = 14 cm