Before I joined WyzAnt, I tutored an AP physics student who contacted me through the physics department. One day, he told me that his physics teacher didn't know how to solve a particular indefinite integral. I eventually wrote out a solution to the problem and used it to introduce the method of trigonometric substitution. Since WyzAnt doesn't support math markup in their blog entries, I will simply post a PDF of the example problem here:

Trigonometric Substitution Example (PDF)

Trigonometric Substitution Example (PDF)

For those who are curious, the PDF was created in LaTeX and the diagram was drawn with the PStricks LaTeX package. If you want to quickly typeset mathematics in order to create your own notes, LaTeX is rather easy to learn. I strongly recommend it! As a graduate student, I typed all of my physics homework assignments using the program,
LyX, which allows for rapid typing of equations because it has many keyboard shortcuts. As an instructor, I still use LyX for rapid note-writing.