Rhomboidicity of Kites

A kite is a quadrilateral with perpendicular diagonals that in certain circumstances is a rhomboid.[br][br]A rhomboid is a kite that in certain circumstances is square.[br][br]Can you devise a measure of rhomboidicity of kites that allows you to tell how much more rhomboidal one kite is than another?[br][br]Can you devise a second and different measure of rhomboidicity of kites? Under what circumstances might one such measure be preferable to the other?[br][br][[i]See the "Polygon Explorer" and "Polygon Synthesizer" applets on the [b]mathMINDhabits[/b] website][/i]

Information: Rhomboidicity of Kites