Решите, , уравнение: корень с 2 sin5x+sin3x-sin7x =0 1+cos2x=2cosx

√2cos5x+sin3x-sin7x=0
√2cos5x+2sin2xcos5x=0

cos5x(√2+2sin2x)=0

cos5x=0
5x=π/2+πn, n € X
x=π/10+πn/5, n € Z

sinx=-√2/2

x=(-1)^k*π/4+πk, k € Z

2) 1+cos2x=2cosx
1+2cos²x-1-2cosx=0

2cos²x-2cosx=0
2cosx(cosx-1)=0
cosx=π/2+πn, n € Z
cosx=1
x=2πn, n € Z