Unable to create a circular polygon with ArcGIS Explorer SDK

Question

I am having trouble creating a circle with a specified radius of 200 feet. I have tried several ways to translate the points along the circular arc.

here is my current code:

var display = ESRI.ArcGISExplorer.Application.Application.ActiveMapDisplay;

var center = display.TrackPoint();
var convertedRadius = Unit.Convert(200, Unit.Feet, center.CoordinateSystem.Unit);    
var firstPoint = GeometryOperations.Move(center, convertedRadius, 0);

var points = new List<Points>();
points.Add(firstPoint);

for (int i = 1; i < 360; i++)
{
    var point = GeometryOperations.Rotate(firstPoint, center, (Math.PI / 180) * i) as Point;
    points.Add(point);
}

var poly = new Polygon(points, display.CurrentCoordinateSystem);
var circleGraphic = new Graphic(poly, Symbol.Fill.Solid.Red);
display.Graphics.Add(circleGraphic);

I only seem to have a problem creating a polygon. Using the above loop I can place 360 markers in a circle around the center point.

Alternately, If there is a way to create a buffer from a point using programmatic methods that would suffice. I am trying to query all shapes that are within 200 feet of a target point.