12.求\( \int_{0}^{\pi} [\sin (2x) \cos x + \cos (2x) \sin x ] dx \) ？ (A) – 2 (B)\(-\frac{2}{3}\)(C)\( \frac{2}{3} \)(D) 2

22.平面上 y = x， y = sin x，x = 0，x =π 所圍區域如圖(一)所示之陰影區域，則其面積可由下列何式求得？ (A) \( \int_{0}^{\pi} (\sin x - x) dx \) (B)\( \int_{0}^{\pi} (x - \sin x) dx \) (C)\( \int_{0}^{\pi} (\sin x + x) dx \)(D)\( 2\int_{0}^{\frac{\pi}{2}} |\sin x - x| dx \)