# acos

(PHP 4, PHP 5, PHP 7)

acosArc cosinus

### Description

acos ( float `\$arg` ) : float

Retourne l'arc cosinus de `arg`. acos() est la fonction inverse de cos(), ce qui signifie que a==cos(acos(a)) pour toute valeur qui soit dans l'intervalle de validité de acos().

### Liste de paramètres

`arg`

L'argument à traiter

### Valeurs de retour

L'arc cosinus de `arg`, en radians.

### Voir aussi add a note

### User Contributed Notes 2 notes

-1
nurlanovic at gmail dot com
1 year ago
``` With this function you can get the number PI.This is done like this: acos(-1) === M_PI ```
-25
zoltan dot szentesi at nokia dot com
12 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! :-) ``` 