tolong jawab ini pake cara ya makasih

1/2 × 22/7 × 21 × 21 = 693

r = d/2 = 42/2 = 21 cm
luas setengah lingkaran
= 1/2 x phi x r²
= 1/2 x 22/7 x 21 x 21
= 1/2 x 22/1 x 3 x 21
= 1/2 x 22 x 3 x 21
= 22 x 3 x 21 / 2 = 66 x 21 / 2 = 1386 / 2 = 693 cm² = C jawabannya