Manipulating (scale & transform) an object in Silverlight

TransformGroup transformGroup = new TransformGroup();

RotateTransform rotateTransform = new RotateTransform();
rotateTransform.Angle = 180;
transformGroup.Children.Add(rotateTransform);

ScaleTransform scaleTransform = new ScaleTransform();
scaleTransform.ScaleX = .50;
scaleTransform.ScaleY = .50;
transformGroup.Children.Add(scaleTransform);

polygon.RenderTransform = transformGroup;

A fuller example here.