Tools and Information

Euclid’s Elements

Uses Java Applets to illustrate and **enhance interactive geometry lessons**. Superb site. All 13 books are on the site, making this a complete geometry course. Free.

Formulas for Areas, Volumes, Surface Areas

List and illustrations.

Free Geometry Help

Browse our collection of* geometry lessons*: Area, Circles, Graphing Lines, Graphing Rational Functions, Slope of a Line.

Geometry – Kahn Academy

This is a first year, high-school level course on Geometry (which is based on Euclid’s elements). It revisits many of the basic geometrical concepts studied in earlier courses, but addresses them with more mathematical rigor. There is strong focus on proving theorems and results from basic postulates.

The Geometry Center

Help learning geometry. Even has courses available.

Geometry Step by Step from the Land of the Incas

It provides an eclectic mix of sound, science, and Incan history intended to interest students in Euclidean geometry. The site includes geometry problems, proofs, quizzes, puzzles, quotations, scientific speculation, and more.

The Golden Mean

The wonder of this number is that artists, mathematicians, architects and scientists have found it uniquely applicable to the physical world. It establishes a singularly pleasing visual balance.

Height Site

How to make an Inclinometer to figure out the height of very tall objects or how high a kite or model rocket has gone. You will use triangles to solve this.

High School Conic Sections, Circles

Stars indicate particularly interesting answers or good places to begin browsing.

Introduction to Geometric Proof

OBJECTIVE: Student will learn the structure of a flow proof.

Student will learn the structure of a statement-reason (two-column) proof.

How To Build A Bookcase

What homeschooling teen doesn’t need another bookcase? Use what you’ve learned about geometry to make sure this case is nice and square. From Popular Mechanics.

Lesson on Circumference of a Circle

The distance around a circle is called the circumference. The distance across a circle through the center is called the diameter. Pi is the ratio of the circumference of a circle to the diameter.

Lines and Polygons

A polygon is a figure that is closed with straight lines, regular or irregular shaped. A line is a straight one-dimensional figure having no thickness and extending infinitely in both directions. I asked the boys to find a polygon in the room. One answer was the rug we were sitting on, the walls, the windows and the best I thought was- the groove in the marble on the fireplace!

The Living Witch of Agnesi

This is a gif animation of the curve known as the ‘Witch of Agnesi.’ It will cycle 5 times showing how the curve is defined graphically using the formula y = a^{3}/(x^{2} + a^{2})

Math.com Homework Help Geometry

Free math lessons and math homework help from basic math to algebra, geometry and beyond. Students, teachers, parents, and everyone can find solutions to their math problems instantly.

Pythagorean Puzzle

Here’s the deal; there was this Greek guy named Pythagoras, who lived over 2,000 years ago during the sixth century B.C.E. Pythagoras spent a lot of time thinking about math, astronomy, and music.

Protractor

Janee made this lovely protractor for you to use on your computer for graphics projects. It could be printed on heavy paper and used offline as well.

Science U’s Geometry Center

Shapes, Patterns, Symmetry! You will find these themes everywhere in the Geometry Center. Browse through an exhibit, or jump right in and start experimenting.

Webmath Geometry

Circles, Squares, Rectangles, Spheres, Cylinders, Boxes, Right triangles, Cones.