出典:Wiktionary
出典:『Wiktionary』 (2008/11/25 22:49 UTC 版)
出典:Wikipedia
出典:『Wikipedia』 (2011/06/26 09:24 UTC 版)
In mathematics, the inverse trigonometric functions or cyclometric functions are the inverse functions of the trigonometric functions, though they do not meet the official definition for inverse functions as their ranges are subsets of the domains of the original functions. Since none of the six trigonometric functions are one-to-one (by failing the horizontal line test), they must be restricted in order to have inverse functions.