I need to get from this:
a^2 / 4*sin(x)*cos(x)
To this:
a^2 * tan(x)
thanks
Just so we are clear is this what you intended in the first post.
$\displaystyle \frac{a^2}{4\sin(x)\cos(x)}=a^2\tan(x)$
you 2nd question does not make sense. An expression cannot be true or false in the first part you wanted to show the above identity was true and it isn't.