cos2x + (sinx)^2 = 0,25

1-2(sinx)^2+(sinx)^2=0.251-(sinx)^2=025(cosx)^2=0.25cosx=0.5                     cosx=-0.5x=+-arccos0.5+2πn      x=+-arccos(-0.5)+2πnx=+-π/3+2πn, n∈Z       x=+-(π-π/3)+2πn, n∈Zx=+-π/3+2πn, n∈Z       x=+-2π/3+2πn, n∈Z