1.Решить уравнения:
а)sin x/2 = 1/2
б)2cos^2x - sin x - 1 = 0
в)2cos^2x - sin x - 1 = 0

2.Найти cos a, если sina =√3/2 и п/4

A) x/2 = (-1)^k*arcsin(1/2) + πkx= ((-1)^k*(π/6) + πk)/2B) 2*cos^2x - sinx - 1 = 02*((1+cos2x)/2) - sinx - 1 = 0Раскроем скобки1 + cos2x - sinx - 1 = 0Cos2x= 1 - 2sin^2x1 - 2sin^2x - sinx = 0Sinx = t2t^2 + t - 1 = 0t1 = -1 t2 = 1/2Sinx = -1 sinx = 1/2X1 = (-1)^k*(3π/2) + πkX2 = (-1)^k*(π/6) + πk