Question

$cos\frac{x}{2} =$±$\sqrt{\frac{1+cosx}{2} }$, if A=$\frac{x}{2}$ then cosA=

Answer 1

Answer:

  $\cos{A}=\pm\sqrt{\dfrac{1+\cos{x}}{2}}$

Step-by-step explanation:

$\cos{A}=\cos{\frac{x}{2}}=\pm\sqrt{\dfrac{1+\cos{x}}{2}}$

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