Find all angles between 0 and $\displaystyle \pi$ for which $\displaystyle 4cos\frac{A}{2}cosAsin\frac{5A}{2}=0$
Just a little question if $\displaystyle
\sin\frac{5A}{2}=0
$, then in what quadrants does A lies in? Does zero means that it is positive or negative?
Edit: Found out that zero is neutral and it belongs to all quadrant.