Question

Cos a= 1/3, найти sin a, tg a, ctg a?

Answer 1

$sin \alpha = \sqrt{1- cos^{2} \alpha } = \sqrt{1-(1/3)^{2}} = \sqrt{1- \frac{1}{9} } = \sqrt{ \frac{8}{9} } = \frac{2 \sqrt{2} }{ 3} \\ tg \alpha = \frac{sin \alpha }{cos \alpha }= \frac{2*3 \sqrt{2} }{3} =2 \sqrt{2} \\ ctg \alpha = \frac{1}{tg \alpha } = \frac{1}{2 \sqrt{2}} = \frac{\sqrt{2}}{4}$