Math's Fun
Sine, Cosine and Tangent are all based on a Right-Angled Triangle. Before doing the functions, it helps to give a name to each side of a right triangle:

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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If you are doing math and don't have a TI Programmable Calculator, you are at a disadvantage.
Texas Instruments TI-83 Plus Graphing Calculator; 64 H x 96mm W Screen