例求下列极限 (1)li tan 3x (2)li 1-cosx x→0tan2x x→0 xsinx x+1-1 arctan 2x (3)lim (4)lim x>0 e2x-1 →0 In(cosx) -2+号 (6)lim esim2x-1+sinx x->0 X xx x x x x x sin cos1 lim)2( 2tan 3tan lim)1( 0 0 − → → 例 求下列极限 3 2 0 0 1 1 arctan 2 (3) lim (4) lim 1 ln(cos ) x x x x x → → e x + − − sin 2 0 1 sin (6) lim x x e x → x − + 2 2 2 (5) lim(2 3)ln( ) x 1 x x →∞ x + +