The solution set of the equation in the given interval is { 1.05, 2.09, 4.19, 5.23}
How to solve the equation?
Here we have the equation:
4*cos²(θ) = 1
Let's isolate θ, we will get:
4*cos²(θ) = 1
cos²(θ) = 1/4
cos(θ) = ±√1/4
cos(θ) = ±1/2
So we will have four solutions, we can apply the inverse cosine function in both sides:
θ = Acos(1/2)= 1.05 and 5.23
θ = Acos(-1/2) = 2.09 and 4.19