Question

дано cosa=-1/3 найти sina tga ctga​

Answer 1

$sin^2\alpha+\cos^2\alpha=1\Rightarrow\sin\alpha=\sqrt{1-\cos^2\alpha}\\\\\sin\alpha=\sqrt{1-\left(-\frac13\right)^2}=\sqrt{1-\frac19}=\sqrt{\frac89}=\pm\frac{2\sqrt2}3\\\\tg\alpha=\frac{\sin\alpha}{\cos\alpha}=\pm\frac{2\sqrt2}3\cdot(-3)=\mp2\sqrt2\\\\ctg\alpha=\frac1{tg\alpha}=\mp\frac1{2\sqrt2}$