Question

Найдите tg, если
a принадлежит (3pi/2 ; 2pi)

Answer 1

Ответ:

$sina=-\dfrac{5}{\sqrt{26}}\\\\\\\displaystyle cos^2a=1-sin^2a=1-\frac{25}{26}=\frac{1}{26}\ \ ,\ \ cosa=\pm \frac{1}{\sqrt{26}}\\\\\\\frac{3\pi}{2}<a<2\pi \ \ \ \to \ \ \ cosa>0\ \ ,\ \ cosa=\frac{1}{\sqrt{26}}\\\\\\tga=\frac{sina}{cosa}=\frac{-5/\sqrt{26}}{1/\sqrt{26}}=-5$