How to calculate the angle between three points based on Latitude/Longitude

Question

Below is the map that captures from Google Map. I want to calculate the angle ABC. I have the coordinate (Latitude/Longitude) of three points.

Is there any approach to resolve my problem?

Thanks

Answer 1

You can find the heading between any two points using the google.maps.geometry.spherical.computeHeading method of the Google Maps Javascript API v3:

computeHeading(from:LatLng, to:LatLng) | number | Returns the heading from one LatLng to another LatLng. Headings are expressed in degrees clockwise from North within the range [-180,180).

The angle between the two will be the difference between the 2 headings.

Example using computeHeading in this answer

Answer 2

You can approximate the angle using the law of cosines. I say approximate because the curvature of the Earth is going to have some non-zero effect on the calculation.

In your example it should suffice to calculate the distances between the points and then perform the appropriate manipulations on the law of cosines. Refer to the second formula in the applications of the law of cosines wiki article and the corresponding picture.