Question

find the exact value of the expression for the given value of theta. do not use a calculator. cos(theta over 2) if theta=5 pi over 3

Answer 1

\[\theta =5\pi/3 \implies \theta/2 = 5\pi/6
\]

Answer 2

This is not a difficult angle to do.

Answer 3

You could use: \[
\cos(\theta/2)= \pm\sqrt{\frac{1+\cos(\theta)}{2}}
\]The \(\pm\) is determined by the quadrant.