Good book recommendations on trigonometry

You might want to look at the following book references:

• Trigonometry, I.M. Gelfand, Mark Saul

• Trigonometry Refresher (Dover Books on Mathematics), A. Albert Klaf, Mathematics

• Schaum's Outline of Trigonometry, 5th Edition, Robert Moyer, Frank Ayres

• Trigonometry, 8th Edition, Ron Larson ($$$)

• Advanced Trigonometry, by C.V. Durell, A. Robson

You might also want to review online items. For example:

• Khan Academy

• Trig WikiBooks

• Open Course Ware on Trigonometry

Enjoy!

Michael Corral's Trigonometry is excellent, building geometric foundations before transitioning to analytical aspects. It also helps that it's absurdly good-looking. It comes with a GNU Free Documentation License too.

Plane Trigonometry by S.L. Loney is the best book for trigonometry.The concepts are explained in a very good manner in the book.