14.求 \( \int_{0}^{\frac{\pi}{2}} x \cos x \, dx \)= ？ (A)\( \frac{\pi}{2} - 1 \) (B)\( \pi - \frac{1}{2} \)(C) \( \frac{\pi}{2} \)(D)\( \frac{\pi}{2} + 1 \)

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)\( 2\int_{0}^{\frac{\pi}{2}} |\sin x - x| dx \)