ACOS function
Description
Arccosine function. ACOS(x) returns the arccosine of x. The arccosine function is the inverse function of the cosine function and calculates the angle for a given cosine. X must be in the [-1..1] range. The result is an angle expressed in radians. To convert from radians to degrees, use the DEGREES function.
The argument x can be a real number, a complex number, or a matrix. When it is a matrix, the function returns a matrix with the same dimensions and with the ACOS function applied to all elements.
Examples
ACOS(0) equals 1.5707963 (=PI/2)
ACOS(1) equals 0
Calculator
Graph

Relation with ASIN and ATAN functions
Related functions
External links
Recommended book
Trigonometry: A Complete Introduction
Hugh Neill
Buy from Amazon
This book covers all areas of trigonometry including the theory and equations of tangent, sine and cosine, using trigonometry in three dimensions and for angles for any magnitude, related to triangles. Everything you will need is here in this one book. Each chapter includes not only an explanation of the knowledge and skills you need, but also worked examples and test questions.