Объяснение:
sin^2x + 2sinx*cosx + cos^2x = 1 + sinx*cosx
1 + 2sinx*cosx = 1 + sinx*cosx
2sinx*cosx - sinx*cosx = 0
sinx*cosx = 0
1) sinx = 0
x = pik, k ∈ Z
2) cosx = 0
x = pi/2+ pik, k∈Z
