Answer:
30° and 150°
Step-by-step explanation:
We want to find the angles in the range:
0° < θ < 360°
Such that:
4*cos^2(θ) - 2 = 1
The first part is to isolate the variable θ in one side of the equation, let's do that:
4*cos^2(θ) = 1 + 2 = 3
cos^2(θ) = 3/4
cos(θ) = ± √(3/4) = ± (√3)/2
Then we have two possible values of θ, one for:
cos(θ) = (√3)/2
And another for
cos(θ) = - (√3)/2
For both cases, we can use the inverse cosine function, Acos(x)
that has the property Acos( cos(x) ) = x
Then:
cos(θ) = (√3)/2
Acos( cos(θ) ) = Acos( (√3)/2)
θ = Acos( (√3)/2) = 30°
And for the other case we have:
θ = Acos( - (√3)/2) = 150°
Then the two values of theta are: 30° and 150°
(We can see that both of these values are in the range 0° < θ < 360°)
