Question

Найти tg^2a,если 3cos^2a-5sin^2a=0

Answer 1

$3cos^{2}a-5sin^{2}a=0$   делим на $3cos^{2}a$ 
$1- frac{5}{3} tg^{2}a=0\ frac{5}{3} tg^{2}a=1\ tg^{2}a= frac{3}{5}$