The answer to the math worksheet question "Who turns out the lights on halloween?" is "the lights witch".
Trigonometry is the study of triangles, which contain angles, of course. Many of the formulas used in trigonometry are also found in algebra and analytic geometry. But trigonometry also has some special formulas usually found just in those discussions.
Check out some special rules for angles and various other important functions, definitions, and translations at Dummies.com.