Question

Cos^2(2theta)+ 2cos(2theta)+1=0

Answer 1

Answer:

θ = π n + π/2 for n element Z

Step-by-step explanation:

Solve for θ:

1 + 2 cos(2 θ) + cos^2(2 θ) = 0

Write the left hand side as a square:

(cos(2 θ) + 1)^2 = 0

Take the square root of both sides:

cos(2 θ) + 1 = 0

Subtract 1 from both sides:

cos(2 θ) = -1

Take the inverse cosine of both sides:

2 θ = 2 π n + π for n element Z

Divide both sides by 2:

Answer:  θ = π n + π/2 for n element Z