נושא : שימוש בזהויות c o s 2 α − cos 4 α s i n 2 α − s i n 4 α = 1 ? c o s 2 α ( 1 − cos 2 α ) s i n 2 α ( 1 − s i n 2 α ) = 1 c o s 2 + s i n 2 = 1 ) c o s 2 α ∗ s i n α s i n 2 α ∗ c o s 2 α ) = 1 1 = 1 {\displaystyle {\begin{aligned}&{\frac {cos^{2}\alpha -\cos ^{4}\alpha }{sin^{2}\alpha -sin^{4}\alpha }}=1?\\&{\frac {cos^{2}\alpha (1-\cos ^{2}\alpha )}{sin^{2}\alpha (1-sin^{2}\alpha )}}=1\\&\color {blue}cos^{2}+sin^{2}=1)\\&{\frac {cos^{2}\alpha *sin^{\alpha }}{sin^{2}\alpha *cos^{2}\alpha )}}=1\\&1=1\\\end{aligned}}}
