-sin x = - cos 2x
-sin x +1-2sin^2(x)=0
2a^2 +a -1 = 0
a = 1/2 a = -1
sin x = 1/2 , x = (-1)^n pi/6 +pin
sin x = -1 x = -pi/2 +2pin
син 3.14/8/sin 3.14/16=sin 0.3925/sin 0.19625=2