Calculating the distance between 2 points in c#

Question

I am trying to sort out a method to calculate the distance between 2 points in c#.

This is the code I have been trying though I fear the answer I get is not correct.

Answer 1

The class I usually use is GeoCoordinate

double latA = -31.997976f;
double longA = 115.762877f;
double latB = -31.99212f;
double longB = 115.763228f;

var locA = new GeoCoordinate(latA, longA);
var locB = new GeoCoordinate(latB, longB);
double distance = locA.GetDistanceTo(locB ); // metres