Question

$tg(x)=-2/3 x=-arctg2/3+\pi*n$ найти из промежутка [-3\pi;-4\pi]

Answer 1

$x=arctg(-\frac{2}{3})+\pi n=-arctg\frac{2}{3}+\pi n,\; n\in Z\\\\x=arctg(-\frac{2}{3})-3\pi =-arctg\frac{2}{3}-3\pi \; \in [\, -3\pi ;-4\pi \, ]$