Drawing library calculate ranges and midpoints to draw a star

Question

I have created a menu that allows users to choose the shape that they wanted to be drawn, then the user click on two points, band the chosen shape will be drawn on that point. I did the triangle this way. But I am not really sure how to draw a star using the same way.

class Triangle : Shape
{
    //This class contains the specific details for a triangle defined in terms of opposite corners
    Point keyPt, oppPt;      // these points identify opposite corners of the triangle

    public Triangle(Point keyPt, Point oppPt)   // constructor
    {
        this.keyPt = keyPt;
        this.oppPt = oppPt;
    }

    public void draw(Graphics g, Pen blackPen)
    {

        double xDiff, yDiff, xMid, yMid;   // range and mid points of x & y  

        // calculate ranges and mid points
        xDiff = oppPt.X - keyPt.X;
        yDiff = oppPt.Y - keyPt.Y;
        xMid = (oppPt.X + keyPt.X) / 2;
        yMid = (oppPt.Y + keyPt.Y) / 2;

        // draw triangle
        g.DrawLine(blackPen, (int)keyPt.X, (int)keyPt.Y, (int)(xMid + yDiff / 2), (int)(yMid - xDiff / 2));
        g.DrawLine(blackPen, (int)(xMid + yDiff / 2), (int)(yMid - xDiff / 2), (int)oppPt.X, (int)oppPt.Y);
        g.DrawLine(blackPen, (int)keyPt.X, (int)keyPt.Y, oppPt.X, oppPt.Y);
    }
}

Appreciate your help.