# Arccosine

Pronunciation: /ɑɹkˈkoʊ.saɪn/ Explain
Abbreviations: acos, arccos

 Figure 1: Arccosine

An arccosine is an angle whose cosine is a particular value. The arccosine is a trigonometric function. The arccosine is the functional inverse of the cosine function. If adjacent/hypotenuse = cosine(θ) then cosine-1(hypotenuse/adjacent) = θ. Arccosine is written arccosin or cos-1.

Definition: y = cos-1 x if and only if x = cos y.

### References

1. McAdams, David E.. All Math Words Dictionary, arccosine. 2nd Classroom edition 20150108-4799968. pg 18. Life is a Story Problem LLC. January 8, 2015. Buy the book

• McAdams, David E.. Cosine. allmathwords.org. Life is a Story Problem LLC. 6/19/2018. http://www.allmathwords.org/c/cosine.html.

McAdams, David E. Arccosine. 4/11/2019. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/a/arccosine.html.

### Revision History

4/11/2019: Changed equations and expressions to new format. (McAdams, David E.)
12/21/2018: Reviewed and corrected IPA pronunication. (McAdams, David E.)