Question

найдите tg a, если cos a=-1/√2 и а є (0,5π; π)

Answer 1

$sin \alpha = - \frac{1}{2} \\ cos \alpha = \sqrt{1 - { (\frac{ - 1}{2}) }^{2} } = \\ \sqrt{ \frac{3}{4} } = - \frac{ \sqrt{3} }{2} \\ tg \alpha = - \frac{1}{2} \div ( - \frac{ \sqrt{3} }{2} ) = \frac{1}{ \sqrt{3} } = \frac{ \sqrt{3} }{3}$