1 + cot 2 α = 1 s i n 2 α = 1 + c o s 2 α s i n 2 α = s i n 2 α + c o s 2 α s i n 2 α = 1 s i n 2 α {\displaystyle {\begin{aligned}1+\cot ^{2}\alpha ={\frac {1}{sin^{2}\alpha }}=1+{\frac {cos^{2}\alpha }{sin^{2}\alpha }}={\frac {sin^{2}\alpha +cos^{2}\alpha }{sin^{2}\alpha }}={\frac {1}{sin^{2}\alpha }}\end{aligned}}}
