Question

3.Найдите значение sina,tga и ctga, если cos a = 5/13



А =​

Answer 1

Ответ:

$cosa=\dfrac{5}{13}\\\\\\\displaystyle sin^2a=1-cos^2a=1-\frac{25}{169}=\frac{144}{169}\ \ ,\ \ sina=\pm \frac{12}{13}\\\\\\tga=\frac{sina}{cosa}=\pm \frac{12}{5}\\\\\\ctga=\frac{1}{tga}=\pm \frac{5}{12}$