Cos(-альфа)cos(180градусов + альфа)/sin(-альфа) * sin(90градусов + 2)

Cos(-α)=cos(α)
cos(π+α)=-cos(α)
sin(-α)= -sin(α)
sin((π/2)+2)= cos(2)
cos(π+α)cos(-α)/(sin(-α)sin((π/2)+2))⇔-cos²(α)/(-sin(α)cos(2))⇔cos²(α)/(sin(α)cos(2))