diff --git a/EGkPolygon3d.h b/EGkPolygon3d.h
index 8829e98..a2c581d 100644
--- a/EGkPolygon3d.h
+++ b/EGkPolygon3d.h
@@ -50,6 +50,9 @@ class Polygon3d
       EGK_EXPORT const PNTVECTOR& GetVertices( void) const
                             { return m_vVert ; }
       EGK_EXPORT PolyLine GetPolyLine( void) const ;
+      EGK_EXPORT Point3d GetCentroid( void) const ;
+      EGK_EXPORT double GetPerimeter( void) const ;
+      EGK_EXPORT double GetArea( void) const ;
 
    public :
       EGK_EXPORT void Translate( const Vector3d& vtMove) ;