Quadrilateral explorer – identifying special quadrilaterals

MathematicsPlane GeometryAges 13–14

Drag the four vertices A, B, C, D, or slide a whole side, on a grid of integer points; the program identifies the shape with complete exactness — parallelogram, rectangle, rhombus, square, trapezoid, isosceles trapezoid, right trapezoid, kite, concave quadrilateral or self-intersecting quadrilateral — and shows the side lengths, angles and both diagonals. Based on the "Quadrilateral" simulation by PhET Interactive Simulations, University of Colorado Boulder (CC BY 4.0); rewritten.

Lesson: Quadrilaterals: trapezoid, isosceles trapezoid, parallelogram, rectangle, rhombus, square