(PHP 4, PHP 5, PHP 7)
Arc cosine
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
Returns:
The arc cosine of arg in radians.
See also:
cos() -
acosh() -
asin() -
atan() -
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