Wolfram Research
Wolfram Math World: Cosine
Graphs of the cosine function, both 2-dimensional and 3-dimensional. Higher level mathematics applications given, including defining the hyperbolic cosine function, the cosine function as an infinite sum and infinite product, and more.
Wolfram Research
Wolfram Math World: Hyperbolic Functions
This site from MathWorld explains the hyperbolic function. The information is not too in-depth, but factual and quite a few links are provided for additional information on related subjects.