[list=1][*]Use [b]Point[/b] (2nd menu) to addfour points A, B, C and D.[br][br][/*][*]Use [b]Polygon[/b] (5th Menu) to create the quadrilateral ABCD.[br][br][/*][*]In the input bar enter: [b]y=x[br][br][/b][/*][*]Use [b]Reflect Object in Line[/b] (9th menu) and select the quadrilateral and the line.[br][/*][/list]