1-cosx 例13求 SIn 1-cos x (1-cos x) (1+cosx 解 L Sm2 r cosx 2(1+cos xJdx 2(x +sin x)+C.例13 . 2 sin 1 cos 2 2 x x x d  − 求 解 x x x x x x x d d   − − + = − (1 cos ) 2 1 (1 cos )(1 cos ) 2 sin 1 cos 2 2 x dx  = 2 (1+ cos ) = 2(x + sin x) + C