Prove that

cos theta / 2 = sqrt[1 + (cos theta / 2)]

I know this is somewhat similar to cosine - half of an angle identity or formula

But I'm having trouble with the division bar, it only divides cos theta not the whole 1 + cos theta. As a result, I can't prove it

Is (1 + cos theta ) / 2 the same to 1 + cos theta /2 ?

Please explain, thanks