## Definition and Usage

The atan() method returns the arctangent of a number as a numeric value between -PI/2 and PI/2 radians.

The atan2() method returns the angle theta of an (x,y) point as a numeric value between -PI and PI radians.

## Syntax

Math.atan(x) Math.atan2(x,y) |

Parameter | Description |

x | Required. A number |

y | Required. A number |

## Example 1 - atan()

The following example returns the arctangent of different numbers with the atan() method:

<script type="text/javascript"> document.write(Math.atan(0.50) + "<br />");
document.write(Math.atan(-0.50) + "<br />");
document.write(Math.atan(5) + "<br />");
document.write(Math.atan(10) + "<br />");
document.write(Math.atan(-5) + "<br />");
document.write(Math.atan(-10)); </script> |

The output of the code above will be:

0.4636476090008061
-0.4636476090008061
1.373400766945016
1.4711276743037347
-1.373400766945016
-1.4711276743037347 |

## Example 2 - atan2()

The following example returns the angle theta of different (x,y) points with the atan2() method:

<script type="text/javascript"> document.write(Math.atan2(0.50,0.50) + "<br />");
document.write(Math.atan2(-0.50,-0.50) + "<br />");
document.write(Math.atan2(5,5) + "<br />");
document.write(Math.atan2(10,20) + "<br />");
document.write(Math.atan2(-5,-5) + "<br />");
document.write(Math.atan2(-10,10)); </script> |

The output of the code above will be:

0.7853981633974483
-2.356194490192345
0.7853981633974483
0.4636476090008061
-2.356194490192345
-0.7853981633974483 |