Question

Найдите tg^2 a если 4sin^2 a+9cos^2 a=6

Answer 1

$4sin^2 a+9cos^2 a=6$
$4sin^2 a+9cos^2 a=6*1$
$4sin^2 a+9cos^2 a=6*(cos^2 a+sin^2 a)$
$4sin^2 a+9cos^2 a=6cos^2 a+6sin^2 a$
$4sin^2 a-6sin^2 a=6cos^2 a-9cos^2 a$
$-2sin^2 a=-3cos^2 a$ | :cos^2 a
$tg^2 a=frac{-3}{-2}=1.5$