Doprowadź do najprostszej postaci: cos a*sin a/ tga sin2 a-1/ cos2 a -1 cos2 a -1 sin a *ctg a

[latex]frac{cos alpha cdot sin alpha }{tg alpha } =cos alpha cdot sin alpha cdot frac{cos alpha }{sin alpha } =cos^2 alpha \\ frac{sin^2 alpha -1}{cos^2 alpha -1}= frac{sin^2 alpha -1}{sin^2 alpha } =1- frac{1}{sin^2 alpha } \\cos^2 alpha -1=sin^2 alpha \\sin alpha cdot ctg alpha =sin alpha cdot frac{cos alpha }{sin alpha } =cos alpha [/latex]