PHP Manual: acos


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acos

(PHP 3, PHP 4, PHP 5)

acos -- Arc cosine

Description

float acos ( float arg )

Returns the arc cosine of arg in radians. acos() is the complementary function of cos(), which means that a==cos(acos(a)) for every value of a that is within acos()' range.

Parameters

arg

The argument to process

Return Values

The arc consine of arg in radians.