sinx 1-cosx 1 m =1×=×1=1 x->0x cos x 例5求 x→ 2 解令t=x-x则当x→时t→0 2 于是 cos cos d lim lim 丌兀 t->0 sin t im t→>0t       − =  → x x x x x x cos sin 1 cos 1 lim 2 0 1 1 2 1 = 1  = 例5 求 x x x − → 2 cos lim 2   解 t = − x 2  令 0 2 则当x → 时t →  于是 x x x − → 2 cos lim 2   t t t ) 2 cos( lim 0 − = →  1 sin lim 0 = = → t t t