2sin^2 x/4+sin π/4 = 2cos^2 π/8 -1

2sin^2 x/4 +√2 /2=1+cos(2* π/8) -1sin^2 x/4  =cosπ/4-√2/2sin^2 x/4=√2/2-√2/2sin^2 x/4=0sinx/4=0x/4=πn, n-celoex=4πn