11
punti
Livello 0
$sin^2 \alpha -tan^2 \alpha=$
$=sin^2 \alpha -\frac{sin^2 \alpha}{cos^2 \alpha}=$
$=sin^2 \alpha -\frac{sin^2 \alpha}{1-sin^2 \alpha}=$
$=\frac{sin^2 \alpha(1-sin^2 \alpha)-sin^2 \alpha}{1-sin^2 \alpha}=$
$=\frac{sin^2 \alpha-sin^4 \alpha-sin^2 \alpha}{1-sin^2 \alpha}=$
$=\frac{-sin^4 \alpha}{1-sin^2 \alpha}=$
$=\frac{sin^4 \alpha}{sin^2 \alpha -1}$
5177
punti
Livello 6