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.
Смотрите также: acosh(), asin(), and atan().