Do you inherit an object of super class in base class when you inherit it?

I have this class which basically represents a point in X-Y plane and has this function to calculate distance between two Point Objects:

double dist(2DPoint p){
return Math.sqrt(Math.pow(x-p.x, 2) + Math.pow(y-p.y, 2));
}

I now want to create a class that represents a point in space in a class 3DPoint. I want to inherit 2d Point and create a function which calculates distance between two 3d points.

I want to do it in such a way that I could use the previous function like this:

double dist(3DPoint p)
{
    return Math.sqrt(Math.pow(z - p.z, 2) + /*Square of dist between X,Y s of the two 3d pts using the dist function from 2DPoint*/);

}

Try this.

class Point2D {
    double x, y;
    double dist(Point2D p) {
        return Math.hypot(x - p.x, y - p.y);
    }
}

class Point3D extends Point2D {
    double z;
    double dist(Point3D p) {
        return Math.hypot(z - p.z, super.dist(p));
    }
}