dnfip:若F(x)=SINX,试证F(X+H)-F(x)=2COS(X+H/2)SINH/2

来源:百度文库 编辑:中科新闻网 时间:2024/05/02 13:35:34

左边=sin(x+h)-sinx
=sinxcosh+cosxsinh-sinx
右边=2<cosxcos(h/2)-sinxsin(h/2)>sin(h/2)
=2<0.5*2cosxcos(h/2)sin(h/2)-sinxsin(h/2)^2>
=cosxsinh-2sinxsin(h/2)^2
=cosxsinh-2sinx(1-cosh)/2
=cosxsinh-sinx+sinxcosh
所以 左边=右边