Answer:
Correct answer: ± √(1+x)/2 = cos Θ/2
Step-by-step explanation:
We know it is:
cos2Θ = cos²Θ - sin²Θ, according to this:
cosΘ = cos²Θ/2 - sin²Θ/2 => cosΘ = cos²Θ/2 - (1 - cos²Θ/2) =>
cosΘ = cos²Θ/2 - 1 + cos²Θ/2 => 1 + cosΘ = 2 cos²Θ/2 =>
cos²Θ/2 = (1 + cosΘ)/2 => cos Θ/2 = ±√(1 + cosΘ)/2 =>
±√(1 + cosΘ)/2 = ± √(1+x)/2 = cos Θ/2
God is with you!!!
