化简:1+sin(x-360度)cos(x-270度)-2cos平方x

问题描述:

化简:1+sin(x-360度)cos(x-270度)-2cos平方x

sin(x-360)=sinx
cos(x-270)=cos(x+90)=-sinx
1=sin^2 x+cos^2 x
1+sin(x-360度)cos(x-270度)-2cos平方x =sin^2 x+cos^2 x-sin^2 x -2cos^2 x=-cos^2 x