php[world] 2018 - Call for Speakers

# acos

(PHP 4, PHP 5, PHP 7)

acosArc cosine

### Descrierea

float acos ( float `\$arg` )

Returns the arc cosine of `arg` in radians. acos() is the inverse function of cos(), which means that a==cos(acos(a)) for every value of a that is within acos()' range.

### Parametri

`arg`

The argument to process

### Valorile întoarse

The arc cosine of `arg` in radians.

add a note

### User Contributed Notes 2 notes

nurlanovic at gmail dot com
6 months ago
``` With this function you can get the number PI.This is done like this: acos(-1) === M_PI ```
-21
zoltan dot szentesi at nokia dot com
11 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! :-) ```