# geo_angle()

Calculates clockwise angle in radians between two lines on Earth. The first line is [point1, point2] and the second line is [point2, point3].

## Syntax

`geo_angle(`p1_longitude`,`p1_latitude`,`p2_longitude`,`p2_latitude`,`p3_longitude`,`p3_latitude`)`

## Parameters

Name Type Required Description
p1_longitude `real` ✔️ The longitude value in degrees of the first geospatial coordinate. A valid value is in the range [-180, +180].
p1_latitude `real` ✔️ The latitude value in degrees of the first geospatial coordinate. A valid value is in the range [-90, +90].
p2_longitude `real` ✔️ The longitude value in degrees of the second geospatial coordinate. A valid value is in the range [-180, +180].
p2_latitude `real` ✔️ The latitude value in degrees of the second geospatial coordinate. A valid value is in the range [-90, +90].
p3_longitude `real` ✔️ The longitude value in degrees of the second geospatial coordinate. A valid value is in the range [-180, +180].
p3_latitude `real` ✔️ The latitude value in degrees of the second geospatial coordinate. A valid value is in the range [-90, +90].

## Returns

An angle in radians in range [0, 2pi) between two lines [p1, p2] and [p2, p3]. The angle is measured CW from the first line to the Second line.

Note

• The geospatial coordinates are interpreted as represented by the WGS-84 coordinate reference system.
• The geodetic datum used to measure distance on Earth is a sphere. Line edges are geodesics on the sphere.
• If the coordinates are invalid, the query will produce a null result.
• If point1 is equal to point2, the query will produce a null result.
• If point2 is equal to point3, the query will produce a null result.
• If point1 and point2 are antipodal, the query will produce a null result.
• If point2 and point3 are antipodal, the query will produce a null result.

## Examples

The following example calculates the angle in radians.

``````print angle_in_radians = geo_angle(0, 10, 0,5, 3,-10)
``````

Output

2.94493843406882

The following example calculates the angle in degrees.

``````let angle_in_radians = geo_angle(0, 10, 0,5, 3,-10);
``````

Output

angle_in_degrees
168.732543198009

The following example returns null because 1st point equals to 2nd point.

``````print is_null = isnull(geo_angle(0, 10, 0, 10, 3, -10))
``````

Output

is_null
True