m[2sin(πx/4-3π/4)+8-2sin(xπ/4-π/4)-6] 那个n是派,不知道能不能显示.怎么化成m[2-2根号2sin（πx/4)

m[2sin(πx/4-3π/4)+8-2sin(xπ/4-π/4)-6] 那个n是派,不知道能不能显示.
怎么化成m[2-2根号2sin（πx/4)

直接把sin(πx/4-3π/4)-sin(xπ/4-π/4)
展开,
用sin(α-β)=sin αcos β-cos αsin β
有sin(πx/4﹚cos(3π/4)-cos(xπ/4)sin(3π/4)-sin(πx/4﹚cos(π/4)+cos(xπ/4)sin(π/4)
并且有sin(π/4)=sin(3π/4)=cos(π/4)=2根号2
cos(3π/4)=-2根号2
最后整个式子就化成了m[2-2根号2sin（πx/4)