The most common functions used in trigonometry are sine, cosine and tangent and are most commonly used when calculating the angle measurements in right triangles. Trigonometry generally
http://www.ehow.com/info_8695793_trigonometricfun...

y = a sin x, talks about amplitude. Example: Electricity is supplied at 240 V, 50 Hz.The graph of this voltage has a period of 0.02 sec & an amplitude of 240 V.
http://www.kgbanswers.com/whatisarealworldexa...

Well, it depends on the function, and furthermore, for each function, there are a number of algorithms, but here's one very simple yet perfectly sufficient algorithm for arguably
http://www.quora.com/Whatisthealgorithmtocomp...
