化简sin(-1071°)*sin99°*sin(-171°)*sin(-261°)1+sin(α-2π)*sin(π+α)-2cos^2(-α)

Question

化简
sin(-1071°)* sin99°*sin(-171°)*sin(-261°)
1+sin(α -2π)*sin(π+α )-2cos^2(-α)

Answer 1

1.sin9°sin99°*sin9°*sin99°=sin^2(99°)*sin^2(sin9°)
2.sin^2(α)+cos^2(α)-sin^2(α)-2cos^2(α)=-cos^2(α)