Доказать тождество:4sinalpha*cosalpha/cos^2alpha-sin^2alpha=2tg2alpha

Question

Доказать тождество:4sinalpha*cosalpha/cos^2alpha-sin^2alpha=2tg2alpha

Answer 1

Cos2alpha=cos^2alpha-sin^2alpha
sin2alpha=2cosalphasinalpha
2sin2alpha/cos2alpha=2tg2alpha