lawofcosine
-----------
lawofcosine is a lightweight plugin written for our extensible shell.
The plugin's usage is as follows: "lawofcosine <side a> <side b> <angle>".
<side a> is the length of a side of triangle, <side b> is the length of 
a side of a triangle, and <angle> is the angle opposite of side c of 
the triangle in degrees. When entering this information, our plugin 
will perform the appropriate calculation or the length of side c 
of the triangle. 

Consider the example at http://www.mathsisfun.com/algebra/trig-cosine-law.html.
Per this example, <side a> is 8, <side b> is 11, and <angle> is 37.
You would run lawofcosine as follows: "lawofcosine 8 11 37". The output
would be "The length of the third side is: 6.666345".

This is implemented using functions from math.h library such as cos() and
sqrt().

lawofcosine is supported on all shells.