tolong bantuin ya kak isi cara juga

A. d = 20cm
r = 10cm
Cara : π ×r× r = 3,14 × 10cm × 10cm = 314cm²
B. d = 30cm
r = 15cm
Cara : π × r × r = 3,14 × 15cm × 15cm = 706,5cm²
C. d = 21cm
r = 10,5cm
Cara : π×r×r =
[tex] \frac{22}{7} \times 10.5 \times 10.5 = {346.5cm}^{2} [/tex]
D. d = 49cm
r = 24,5cm
Caranya : π × r × r = 22/7×24,5 × 24,5= 1886,5 cm²