Quandaries
and Queries 

Name: Kyle Student, Secondary Question I would like to know how to evaluate the problem of: Arccos 5/13. Thank you. 

Hi Kyle, I expect that what you want is some trig function of arccos(5/13), like maybe
I would start by drawing a triangle.
In this diagram the angle ABC has a cosine of 5/13. In other words
By Pythagoras' theorem
that is
Now you can read the trig functions of angle ABC from the diagram, for example
I hope this helps, 

