Question

Найдите тригонометрическое неравенство 2cos(x+п/3)< -1

Answer 1

$cos(x+ \frac{ \pi }{3})\ \textless \ -0.5$
$\frac{2 \pi }{3}+2 \pi k\ \textless \ x+ \frac{ \pi }{3}\ \textless \ \frac{4 \pi }{3}+2 \pi k$
$\frac{\pi }{3}+2 \pi k\ \textless \ x\ \textless \ \pi +2 \pi k$
k∈Z

Answer 2

Cos(x+π/3)<-1/2
2π/3+2πn<x+π/3<4π/3+2πn
π/3+2πn<x<π+2πn
x∈(π/3+2πn;π+2πn)