Question

Только 3 задание буду благодарен

Answer 1

Ответ:

$3a)\ \ \displaystyle cosa=-\frac{3}{5}\ \ ,\\\\\frac{\pi}{2}<a<\pi \ \ \ \to \ \ \ sina>0\ \ ,\ \ sina=+\sqrt{1-cos^2a}\\\\sina=\sqrt{1-\frac{9}{25}}=\sqrt{\frac{16}{25}}=\frac{4}{5}\\\\tga=\frac{sina}{cosa}=\frac{4/5}{-3/5}=-\frac{4}{3}\\\\ctga=\frac{1}{tga}=-\frac{3}{4}$

$3b)\ \ \displaystyle sina=-0,6=-\frac{3}{5}\ \ ,\\\\\frac{3\pi}{2}<a<2\pi \ \ \ \to \ \ \ cosa>0\ \ ,\ \ cosa=+\sqrt{1-sin^2a}\\\\sina=\sqrt{1-\frac{9}{25}}=\sqrt{\frac{16}{25}}=\frac{4}{5}\\\\tga=\frac{sina}{cosa}=\frac{-3/5}{4/5}=-\frac{3}{4}\\\\ctga=\frac{1}{tga}=-\frac{4}{3}$