Make a 2D or 3D window and write the equation into Grapher. You can also use Grapher's different symbols. When you are finished, highlight the equation and command-click (right-click) and simply select "Copy LaTeX Expression." Now paste it into LaTeX

For example, it turned this equation:

` y^(1/2)=cosx^2+cosz^3 `

Into this equation:
` y^{\left( \frac{1}{2} \right)}=\cos x^{2}+\cos z^{3} `

[**robg adds:**I haven't tested this one, but there are quite a few hints here on using LaTex with OS X. Also, in trying to understand LaTex better, I found this page, which has a ton of links to LaTex resources, as well as a nice one-page overview of LaTex.]