Question

Срочно 20 балов
1) 1- cos ^2a=?
2) cos a tag a = ?
3) 1/cos^2a - 1=?

Answer 1

$1)1-Cos^{2}alpha=Sin^{2} alpha\\2)Cosalpha*tgalpha=Cosalpha*frac{Sinalpha }{Cosalpha}=Sinalpha\\3)frac{1}{Cos^{2}alpha} -1=frac{1-Cos^{2}alpha}{Cos^{2}alpha}=frac{Sin^{2}alpha }{Cos^{2}alpha}=tg^{2}alpha$