Ctg 3a - tg 3a = выразите

[latex]ctg 3a-tg 3a= \frac{cos 3a}{sin 3a} - \frac{sin 3a}{cos3a}= \frac{cos^2 3a-sin^2 3a}{sin3a*cos3a}= \frac{cos 6a}{ \frac{1}{2}sin 6a } =2ctg 6a[/latex]