luas bangun tersebut adalah

d^2 = (26-14)^2 + 16^2
d^2 = 12^2 + 16^2
d^2 = 144+256
d = √144+256
d = √400
d = 20 cm
r = 10 cm

L 1/2 lingkaran = 1/2 π r r
= 1/2 x 3,14 x 10 x 10
= 1/2 x 314
= 157 cm^2

L trapesium = 1/2 (a+b) t
= 1/2 (14+26) 16
= 40 x 8
= 320 cm^2

L bangun = L 1/2 lingkaran + L trapesium
= 157+320
= 477 cm^2
(jawabannya C)

*semoga membantu. sukses selalu ^_^