kirichekov

Verified answer

Cos2x+sin²x=0,75
cos²x-sin²x+sin²x=0,75
cos²x=0,75
cos²x=3/4
cosx=+-√(3/4)
1. cos=-√3/2. x=+-arccos(-√3/2)+2πn,n ∈Z. x=+-(π-arccos(√3/2)+2πn, n∈Z. 
x₁=+-5π/6+2πn, n∈Z
2. cosx=√3/2. x=+-arccos(√3/2)+2πn, n∈X.                      x₂=+-π/6+2πn, n∈Z

ответ: x₁=+-5π/6+2πn, n∈Z , x₂=+-π/6+2πn, n∈Z