Internet Resources for the preCalculus Student

"Mathman" Don Cohen has a web site including many examples of kids (and adults) having fun with math. One of Don's pictures relates a geometric series to the area of a triangle. Can you see how to extend his idea to find the volume of a pyramid?

Don's picture leads in many directions - both geometric and algebraic

eg
    Does the triangle have to be right angled? (isoceles is also pretty)

    And the factorization r+r^2+r^3+.... = (r+r^2)(1+r^2+r^4+...)
    generalizes to eg (r+r^2+r^3)(1+r^3+r^9+...)
    Is there a 3d picture corresponding to this?

    Next thing you know we have the volume of a pyramid - without using
calculus.
    Amazing!