How do I merge polygons (latitude & longitude)?

I have polygons defined on a map with latitude & longitude as the coordinate system. I want to merge all overlapping polygons.

From this question Question

I found this software: Software

I downloaded the code an it works great for Cartesian coordinates. But, I have no idea how to utilize it for latitude & longitude.

Whats the best way to approach this problem?

For example here are the polygons I want to merge:

        var polyA = new List<GpsLocation>();
        var pA1 = new GpsLocation(0, 0);
        polyA.Add(pA1);
        var pA2 = GpsHelper.CreateLocationBasedOnBearingDistance(pA1, 5, 100);
        polyA.Add(pA2);
        var pA3 = GpsHelper.CreateLocationBasedOnBearingDistance(pA2, 95, 100);
        polyA.Add(pA3);
        var pA4 = GpsHelper.CreateLocationBasedOnBearingDistance(pA3, 185, 100);
        polyA.Add(pA4);

        var polyB = new List<GpsLocation>();

        var pB1 = GpsHelper.CreateLocationBasedOnBearingDistance(pA1, 95, 50);
        polyB.Add(pB1);
        var pB2 = GpsHelper.CreateLocationBasedOnBearingDistance(pB1, 5, 100);
        polyB.Add(pB2);
        var pB3 = GpsHelper.CreateLocationBasedOnBearingDistance(pB2, 95, 100);
        polyB.Add(pB3);
        var pB4 = GpsHelper.CreateLocationBasedOnBearingDistance(pB3, 185, 100);
        polyB.Add(pB4);