Cool Math
Coolmath: Precalculus Basic Formulas to Know
This CoolMath resource provides an introduction to some Precalculus formulas.
Math Open Reference
Math Open Reference: Quadrilaterals
A complete reference guide to quadrilaterals including squares, rectangles, parallelograms, trapezoids, and rhombus. It provides definitions and interactive activities that enhance further explanation.
BBC
Bbc: Bitesize: Maths: 2 D Shapes
Learn about the properties of 2-D shapes: circles, triangles, polygons, and quadrilaterals. Includes information, video, and examples about each, with games and quizzes for reinforcement.