Question

The expression cosine of pi over 2 times cosine of pi over 3 plus sine of pi over 2 times sine of pi over 3 can be rewritten as which of the following?

Answer 1

Solution:

Given;

$\cos\frac{\pi}{2}\cos\frac{\pi}{3}+\sin\frac{\pi}{2}\sin\frac{\pi}{3}$

Using the identities;

Thus;

$\begin{gathered} \cos\frac{\pi}{2}\cos\frac{\pi}{3}+\sin\frac{\pi}{2}\sin\frac{\pi}{3}=\cos(\frac{\pi}{2}-\frac{\pi}{3}) \\ \\ \cos\frac{\pi}{2}\cos\frac{\pi}{3}+\sin\frac{\pi}{2}\sin\frac{\pi}{3}=\cos(\frac{\pi}{6}) \end{gathered}$

CORRECT OPTION: A