Tentukan luas daerah yng diarsir dari gambar brikut

3. a. Luas 1/2 lingkaran
= 1/2 × phi × r^2
= 1/2 × phi × (20^2 – 16^2)
= 1/2 × phi × (400 – 256)
= 1/2 × 144 × 3,14
= 72 × 3,14
= 226,8

b. L. segitiga 1 + L. segitiga 2
= 1/2 × a1 × t1 + 1/2 × a1 × t2
= 1/2 × 12 × (20^2 – 12^2)^1/2 + 1/2 × 15 × 20
= 6 × (400 – 144)^1/2 + 10 × 15
= 6 × (256)^1/2 + 150
= 6 × 16 + 150
= 96 + 150
= 246 cm^2

P.S. : …^1/2 = akar kuadrat dari …