Question

Для острого угла а, найдите sina, tga, ctga a, если cosa=12/13

Answer 1

$\sin \alpha = \sqrt{1 - { \cos }^{2} \alpha } = \sqrt{1 - {( \frac{12}{13} )}^{2} } = \sqrt{1 - \frac{144}{169} } = \sqrt{ \frac{25}{169} } = \frac{5}{13}$

$\tan \alpha = \frac{ \sin \alpha }{ \cos \alpha } = \frac{ \frac{5}{13} }{ \frac{12}{13} } = \frac{5}{13} \times \frac{13}{12} = \frac{5}{12}$

$\cot \alpha = \frac{1}{ \tan \alpha } = \frac{1}{ \frac{5}{12} } = \frac{12}{5}$