化简2sin^2(x)sin^2(φ)+2cos^2(x)cos^2(φ)-cos2(x)cos^2(φ)
问题描述：
化简2sin^2(x)sin^2(φ)+2cos^2(x)cos^2(φ)-cos2(x)cos^2(φ)
答
据:cos2(x)=cosx^2-sinx^2=2cosx^2-1得:2sin^2(x)sin^2(φ)+2cos^2(x)cos^2(φ)-cos2(x)cos^2(φ)=2sin^2(x)sin^2(φ)+cos^2(φ)=(2sin^2(x)-1)*sin^2(φ)+sin^2(φ)+cos^2(φ)=(sin^2(x)-cos^2(x))*sin^2(φ)+1=-co...