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.
See also:
acosh(),
asin(), and
atan().