This website will help you with squares and their properties. Such as side length, diagonal length, area and perimeter.
WebMath

This page gives two methods for finding the area of a kite: a geometry formula and a trigonometric formula. Numerous connected pages offer a wide variety of information on all types of polygons.
Math Open Reference

A helpful scientific calculator that runs in your web browser window.
Holt Online Learning

Worksheet to practice calculating surface area for rectangular prisms.
Helping with Math

Worksheet to practice using the formula for the area of a circle.
Helping with Math

A page with links for properties of circles and different types of polygons. Each link has great visuals with clear markings, definitions, and formulas.
Cool Math

Comprehensive list of formulas for finding the area, volume and surface area of various shapes.
Math2

Formulas with corresponding pictures, help tutors and student review all the area fomula of plane shapes
Math is fun

Area enclosed by a circle. Definition and formula
Math Open Reference

This page will help you to calculate things related to a rectangle. Such as length, width, perimeter, area, and the length of the diagonal.
WebMath
