Last problem in my homework, and I get stuck on it :/
cos^2(θ/2) = (1+cosθ)/√(2)
cos^2(θ/2) = (1-cosθ)/√(2)
cos^2(θ/2) = (1-cosθ)/2
cos^2(θ/2) = (1+cosθ)/2
cos^2(θ/2) = (1+cosθ)/√(2)
cos^2(θ/2) = (1-cosθ)/√(2)
cos^2(θ/2) = (1-cosθ)/2
cos^2(θ/2) = (1+cosθ)/2
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Use cos2x = 2 cos^2 x - 1
so cos x = 2 cos^2 x/2 - 1
cos x +1 = 2 cos^2 (x/2)
( cos x + 1) / 2 = cos^2 (x/2)
so cos ^2 ( θ/2) = ( ( cos θ + 1 ) /2
so cos x = 2 cos^2 x/2 - 1
cos x +1 = 2 cos^2 (x/2)
( cos x + 1) / 2 = cos^2 (x/2)
so cos ^2 ( θ/2) = ( ( cos θ + 1 ) /2