例2求2 cos'xsin xdx cos'xsinxdcos(cos x) -2 1-6 0 9 9 例 2 求 2 5 0 cos sin x xdx   解 2 2 5 5 0 0 cos sin cos (cos ) x xdx x x dx   = −    2 5 6 0 1 1 cos cos cos 2 6 6 0 xd x x   = − = − = 