⑩天掌 Teaching Plan on Advanced Mathematics 上式对于-<x<0也成立当0<x<时, 0<c0sx-1=1-cx=2sin2x∠2/,)2 222 2 lim -=0,. lim(1-cos x)=0, →02 x→0 lim cos x=1,又∴lim1=1, x→0 x→0 sInx lim x→>0x tan x 例11求lm 0xTianjin Polytechnic University Teaching Plan on Advanced Mathematics 0 . 2 上式对于   也成立  − x , 2 当 0 时   x  0  cos x − 1 = 1 − cos x 2 2sin2 x = 2 ) 2 2( x  , 2 2 x = 0, 2 lim 2 0 = → x x  lim(1 cos ) 0, 0  − = → x x limcos 1, 0  = → x x lim1 1, 0 = x→ 又 1. sin lim 0  = → x x x 例11 求 x x x tan lim →0