Create Conic Section of Ellipse

We consider the points A (-15.15), B (0.15) . We create the line segment AB with fixed length a = 15. We consider point C on it. In the algebra's window of software we could calcuale distances AC = d1 and BC = d2. We consider variable c and points C (-c, 0) and E (c, 0). Manufactured circle C1 with center E' and radius d2, and circle C2 with center E and radius d1. We call M and N the intersection points. Notice the geometric construction of the shape displayed