I had no idea that changing page margin size can cause problems with line break with in-line math. I have this MWE that shows one problem.
I like to make the page margins smaller, so I can fit more things on the page. But when I do that, sometimes I notice problems, like this:

\documentclass[12pt]{article}
%uncommenting this line below shows the problem
%\usepackage[left=.7in,right=.7in,top=.9in,bottom=.9in]{geometry}
\begin{document}
So the point $p$ appears to move is the opposite direction with tangential
acceleration $-\left( \sqrt{13}\dot{\omega}_{3}\right) \sin\theta
\mathbf{i-}\left( \sqrt{13}\dot{\omega}_{3}\right) \cos\theta\mathbf{k}$ and
normal acceleration $-\left( \sqrt{13}\omega_{3}^{2}\right) \cos
\theta\mathbf{i+}\left( \sqrt{13}\omega_{3}^{2}\right) \sin\theta\mathbf{k}$
Where $\theta=\tan^{-1}\left( \frac{3}{2}\right) $, hence $\cos\theta
=\frac{2}{\sqrt{13}}$ and $\sin\theta=\frac{3}{\sqrt{13}}$therefore%
\end{document}
Using TL 2013. ps. code above is auto-generated.
Do I really have to worry about these problems if I change page size? I thought Latex math breaking algorithm is supposed to take care of these things automatically? Or Am I doing something wrong?
\left..\rightso if you want line breaking you should remove most of those. (there is also a space missing beforetherefore) – David Carlisle Oct 22 '13 at 22:59$r\sin\theta...$instead of writing the explicit value. – Thruston Oct 22 '13 at 22:59\leftand\rightbefore all delimiters is a good thing. To the contrary, it is a bad thing, because it freezes spaces around binary operators so they can't participate to the space adjustments for justification and they make the formula unbreakable inside them. In this particular case, after removing them still an overfull line is produced: you're unlucky because you have to quite long formulas near to each other. – egreg Oct 22 '13 at 23:12