Question

решите неравенство:4соs^2x-3>0

Answer 1

$4cos^2x-3 textgreater 0\\cos^2x textgreater frac{3}{4}\\frac{1+cos2x}{2} textgreater frac{3}{4}\\1+cos2x textgreater frac{3}{2}\\cos2x textgreater frac{1}{2}\\-frac{pi}{3}+2pi n textless 2x textless frac{pi}{3}+2pi n; ,; nin Z\\-frac{pi}{6}+pi n textless x textless frac{pi}{6}+pi n; ,; nin Z\\P.S.quad Formyla:; ; ; cos^2x=frac{1+cos2x}{2}$