find the surface area of a regular polygon circumscribed around a sphere in csharp

main.cs
int numSides = 6; // for example
double radius = 5.0; // for example
Vector3D[] vertices = new Vector3D[numSides];
for (int i = 0; i < numSides; i++)
{
    double angle = 2.0 * Math.PI * i / numSides;
    double x = radius * Math.Cos(angle);
    double y = radius * Math.Sin(angle);
    vertices[i] = new Vector3D(x, y, 0.0);
}
328 chars
11 lines

main.cs
double[] sideLengths = new double[numSides];
for (int i = 0; i < numSides; i++)
{
    Vector3D diff = vertices[(i+1)%numSides] - vertices[i];
    sideLengths[i] = diff.Length;
}
178 chars
7 lines

main.cs
double[] faceAreas = new double[numSides];
double s = 0.5 * sideLengths.Sum();
for (int i = 0; i < numSides; i++)
{
    double a = sideLengths[(i+numSides-1)%numSides];
    double b = sideLengths[i];
    double c = sideLengths[(i+1)%numSides];
    double area = Math.Sqrt(s * (s-a) * (s-b) * (s-c));
    faceAreas[i] = area;
}
327 chars
11 lines

main.cs
double totalArea = faceAreas.Sum();
36 chars
2 lines