Kak gimana nih Caranya ???

L bangun = L1/2 lingkaran + L trapesium
L 1/2 lingkaran = 1/2 phi r²
= 1/2 x 3,14 x 10² = 157

L trapesium = 1/2 x (a+b) x t
= 1/2 (20+28) x 10
= 1/2 (48) x 10
= 240

L bangun = 157 + 240 = 397 cm²