pake cara nya ya kak..... tolong bantu

12) L 1 = s × s = 20 × 20 = 400 cm²

L2 = ½ × π × r²
= ½ × 3,14 × 10 × 10
= 157 cm²

L3 = ½ × a × t
= ½ × 20 × 8
= 80 cm²

Lb = L1 - L2 - L3
= 400 - 157 - 80
= 163 cm²

L persegi = s² = 20² = 20 x 20= 400 dm²
L segitiga = 1/2 x a x t
= 1/2 x 20 x 8 = 10 x 8 = 80 dm²
L 1/2 lingkaran
= 1/2 x 3,14 x 10 x 10
= 1,57 x 10 x 10
= 157 dm²

= L persegi - ( L segitiga + L 1/2 lingkaran)
= 400 - (80+157)
= 400 - 237
= 163 dm²