Question

Помогите. Тригонометрия

Answer 1

$1)quad sinx leq 0\\-pi +2pi n leq x leq 2pi n; ,; nin Z\\2)quad cos^2x textgreater frac{1}{2}\\frac{1+cos2x}{2} textgreater frac{1}{2}\\frac{cos2x}{2} textgreater 0\\cos2x textgreater 0\\-frac{pi}{2}+2pi nleq 2x leq frac{pi}{2}+2pi n; ,; nin Z\\-frac{pi}{4}+pi nleq xleq frac{pi}{4}+pi n; ,; nin Z$