How to create a circle with ArcEngine?

EllipticArcClass ellipticalArc = new EllipticArcClass();
 
IEnvelope env = new EnvelopeClass();
 
IPoint lowerLeft = new PointClass();
 
lowerLeft.X = centerPoint.X - width;
 
lowerLeft.Y = centerPoint.Y - height;
 
IPoint upperRight = new PointClass();
 
upperRight.X = centerPoint.X + width;
 
upperRight.Y = centerPoint.Y + height;
 
env.LowerLeft = lowerLeft;
 
env.UpperRight = upperRight;
 
ellipticalArc.ConstructEnvelope(env);
 
IGraphicTrackerSymbol graphicTrackerSymbol = this.graphicTracker.CreateSymbol(simpleFillSymbol, null);
 
int shapeId = this.graphicTracker.Add(ellipticalArc, graphicTrackerSymbol);