Question

Найдите tg(α), если sin= $\frac{3}{\sqrt{10} }$

Answer 1

$sina=\frac{3}{\sqrt{10}}>0\; \; \Rightarrow \; \; a\in (2\pi n\,;\pi +2\pi n)\\\\\boxed{sin^2a+cos^2a=1}\; \; \to \; \; cos^2a=1-sin^2a=1-\frac{9}{10}=\frac{1}{10}\; ,\; \; cosa=\pm \frac{1}{\sqrt{10}}\\\\\boxed {tga=\frac{sina}{cosa}}\; \; ,\; \; tga=\frac{\frac{3}{\sqrt{10}}}{\pm \frac{1}{\sqrt{10}}}=\pm \frac{3}{1}=\pm 3\\\\\\Esli\; \; a\in (2\pi n\, ;\frac{\pi }{2}+2\pi n)\; ,\; to\; \; tga=3\; .\\\\Esli\; a\in (\frac{\pi}{2}+2\pi n\, ;\pi +2\pi n)\; \; ,\; to \; \; tga=-3\; .$