3sin([latex] \pi [/latex]-α)cos([latex]\pi [/latex]/2 - α)+3sin²([latex]\pi [/latex]/2-α)

[latex]3sin( \pi - \alpha )*cos( \frac{ \pi }{2} - \alpha )+3sin^2( \frac{ \pi }{2} - \alpha )=3sin \alpha *sin \alpha +3cos^2 \alpha =[/latex][latex]=3sin^2 \alpha +3cos^2 \alpha =3(sin^2 \alpha +cos^2 \alpha )=3*1=3[/latex] [latex]cos^2x+sin^2x=1[/latex]