tolong dijawab pakai cara... secepatnya terima kasih

a. 20^2 - 16^2 =
400 - 256 = akar 144
akar 144 = 12

r = 6

1/2 lingkaran = 1/2 x 3,14 x 6^2
= 1/2 x 3,14 x 36
= 56, 52 cm^2

b. B1 = AC - AD
= 20^2 - 12^2
= 400 - 144
= akar 256 = 16
luas = 1/2.a.t
=1/2 x 12 x 16
= 96 cm^2

maaf kalau salah