Question

Dado tg ∝ = 5/12, calcula cos 2∝

Answer 1

Explicación paso a paso:

$cos2 \alpha = {cos}^{2} \alpha - {sen}^{2} \alpha \\ \cos(2 \alpha ) = { (\frac{12}{13} )}^{2} - {( \frac{5}{13}) }^{2} \\ \cos(2 \alpha ) = \frac{144}{169} - \frac{25}{169} \\ \cos( 2\alpha ) = \frac{144 - 25}{169} \\ \cos( 2\alpha ) = \frac{119}{169}$