Use the half-angle formula to simplify the given expression.

squareroot 1+cos12x/2

3 answers

did you even look up your half-angle formula? It says that

cos(θ/2) = √[(1+cosθ)/2]

I think the substitution is now clear.
is it cos12x?
No.

You are half right. θ=12x is the right substitution to use, but if θ = 12x, what you have is cos(θ/2) = cos 6x