Question

True or false. cos(a/2)=sqrt(1-cos(a)/2) for all vaules of a.

Answer 1

seems unlikely, since cosine can be negative

Answer 2

actually now that i look, the whole thing is wrong
\[\cos(\frac{\alpha}{2})=\pm\sqrt{\frac{1+\cos(\alpha)}{2}}\]

Answer 3

SO THEN IT WOULD BE FALSE?

Answer 4

definitely

Answer 5

THANKS!