f(x)=sin(x+b)+cos(x-b)为偶函数,则b等于多少

问题描述:

f(x)=sin(x+b)+cos(x-b)为偶函数,则b等于多少

因为它是偶函数,所以有f(x)=f(-x)sin(x+b)+cos(x-b)=sin(-x+b)+cos(-x-b)sinxcosb+sinbcosx+cosxcosb+sinxsinb=-sinxcosb+sinbcosx+cosxcosb-sinx...