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Brown Math: Remembering Trig Identities
Faced with a large number of trigonometric identities, students tend to try to memorize them all. This site the emphasis is on understanding how the functions work and on memorizing only about a half dozen of them - all the others work...
Johan Claeys
Math Abundance: Inverse Trigonometric Functions = Cyclometric Functions
Explains the inverse trigonometric functions using examples.