Question

Вычислите sin a,tg a, если соs a =-3/4 и π/2

Answer 1

$\frac{\pi} {2}< \alpha< \pi \\\\Sin\alpha>0\\\\Sin \alpha= \sqrt{1-Cos^{2}\alpha} = \sqrt{1-(-\frac{3}{4})^{2}}= \sqrt{1-\frac{9}{16}}= \sqrt{\frac{7}{16}}= \frac{\sqrt{7}} {4}\\\\tg\alpha =\frac{Sin\alpha} {Cos\alpha} = \frac{\sqrt{7}} {4}: (-\frac{3}{4})=- \frac{\sqrt{7} } {4}* \frac{4}{3}=- \frac{\sqrt{7}} {3}$

Answer 2

Решение во вложении...