Cos(x)/(2) =±\sqrt{(1+cosx)/(2) }, if A=(x)/(2) then cosA=

Question

`cos(x)/(2) =`±
`\sqrt{(1+cosx)/(2) }`, if A=
`(x)/(2)` then cosA=

Answer 1

`cos(A)=\pm\sqrt{(1+cos(x))/(2)}`

Explanation:

`cos(A)=\cos{(x)/(2)}=\pm\sqrt{(1+cos(x))/(2)}`

Apparently, you're supposed to recognize that the formula tells you the value of cos(x/2).