Решите тригонометрические неравенства.(c помощью единичной окружности)
а)[tex]cos \frac{2x}{3} \ \textless \ - \frac{ \sqrt{2} }{2} [/tex]
б)[tex]2sin \frac{x}{4} cos \frac{x}{4} \ \textgreater \ - \frac{1}{2} [/tex]

1)3π/4+2πn<2x/3<5π/4+2πn9π/8+3πn<x<15π/8+3πn2)2sinx/4*cosx/4=sinx/2>-1/2-π/6+2πn<x/2<7π/6+2πn-π/3+4πn<x<7π/3+4πn

а) cos2x/3 < -√2/2 ;π -π/4 < 2x/3 < π +π/4 ;3π/4 <2x/3 <5π/4 ;2πk+3π/4 <2x/3 <5π/4 +2πk ;3πk +9π/8 < x <15π/8 +3πk , k∈ Z.б) 2sinx/4cosx/4 > -1/2 'sin2*x/4 > -1/2; - π/6 < x/2 < π +π/6; - π/6 < x/2 < 7π/6;2πk  - π/6 < x/2 <7π/6  +2πk ;4πk -π/3 < x <  7π/3 +4πk , k∈ Z- π/3 +4πk  < x <  7π/3 +4πk , k∈ Z.в любом  интервалеx ∈(- π/3 +4πk ;  7π/3 +4πk )  , k∈ Z.