public void QueryOutline(IDisplay Display, IPolygon Outline)
{
//return a polygon which is the outline of the element
IPolygon polygon = new PolygonClass();
polygon.SetEmpty();
((ISymbol)m_fillSymbol).QueryBoundary(Display.hDC, Display.DisplayTransformation, m_triangle, polygon);
((IPointCollection)Outline).AddPointCollection((IPointCollection)polygon);
}