This example shows how to use the free Linux Libertine fonts on writeLaTeX. The Libertine font family provides serif fonts similar to Times New Roman.
The source code is based on The LaTeX Font Catalogue.
Following on from example 4 which showed how to plot the graph of a function in LaTeX using pstricks, here we extend the example to show how trig functions such as cos, sin and tan can be plotted.
Original source: http://www.thelazymathematician.com/p/pstricks-examples.html