Question

найдите tga если cosa корень 17/17

Answer 1

$\cos a = \frac{\sqrt{17}}{17}\\ \\ \cos^2 a = \frac{17}{17^2} = \frac{1}{17}\\ \\ \tan^2 a = \frac{sin^2 a}{\cos^2 a} = \frac{1-\cos^2 a}{\cos^2 a}= \\ =\frac{1 - 1/17}{1/17}=\frac{16/17}{1/17}=16\\ \\ \tan a = \pm \sqrt{16} = \pm 4$