CakeFest 2017 NYC, the Official CakePHP Conference


(PHP 4, PHP 5, PHP 7)

acosArc 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.



The argument to process

Return Values

The arc cosine of arg in radians.

See Also

add a note add a note

User Contributed Notes 1 note

zoltan dot szentesi at nokia dot com
10 years ago
Wondering what is the use of 'acos' function?

It is essential in games, animations and drawings to determine the location of two objects relating to each other.

To the point: the angle of two vectors is calculated by

           v1X*v2X + v1Y*v2Y
  acos(--------------------------)=angle between two vectors.
               |v1| * |v2|

|v1| and |v2| are the length of the vectors and calculated using Pithagoras-formula: |v1|=sqrt(v1X*v1X + v1Y*v1Y)

This helped me to calculate and share given space for 'n' amount of objects so that they don't overlap.

Enjoy! :-)
To Top