arc-hyperbolic cosine

arc-hyperbolic cosine [‚ärk ‚hī·pər‚bäl·ik ′kō‚sīn]

(mathematics)

Also known as inverse hyperbolic cosine.

For a number,x, equal to or greater than 1, either of the two numbers whose hyperbolic cosine equalsx.

For a number,x, equal to or greater than 1, the positive number whose hyperbolic cosine equalsx; it is the value atxof the restriction of the inverse of the hyperbolic cosine function to the positive numbers.