Convert an angle in Degrees to Radians in C#

May 17, 2010 | Code Snippets, Thoughts from the team

I was recently using Google Maps API geo-location lookups to get the longitude and latitude of an address entered by the user.  I wanted to find the distance between a two co-ordinates using the Haversine Formula.  To do this I needed to convert my lat/lng co-ordinates into radians.  This seemed like an excellent opportunity to create a new extension method to add to Storm‘s library of re-usable code.

The maths to convert an angle from degrees to radians is really quite simple:

(pi / 180) * angle

We can take this simple equation and create either a simple function, or a convenient extension method.

C# Function

    public double ConvertToRadians(double angle)
        return (Math.PI / 180) * angle;

C# Extension Method

    /// <summary>
    /// Convert to Radians.
    /// </summary>
    /// <param name="val">The value to convert to radians</param>
    /// <returns>The value in radians</returns>
    public static class NumericExtensions
        public static double ToRadians(this double val)
            return (Math.PI / 180) * val;

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