Question

докажите логарифмическое тождество

Answer 1

Объяснение:

$\frac{cos 2a}{cos^2a}=\frac{cos^2a-sin^2a}{cos^2a}= 1-tg^2a$

Answer 2

$1-tg^{2}\alpha=1-\frac{Sin^{2}\alpha}{Cos^{2}\alpha}=\frac{Cos^{2}\alpha-Sin^{2}\alpha}{Cos^{2}\alpha}=\frac{Cos2\alpha}{Cos^{2}\alpha}\\\\\frac{Cos2\alpha}{Cos^{2}\alpha}=\frac{Cos2\alpha}{Cos^{2}\alpha}$

Тождество доказано