# Category Archive: geometry

Nov 18

## A couple useful 3D diagrams

Useful diagrams. Click to open the Word file: 3d-diagrams

Dec 01

## 3D Shapes video

Nice 3D Shapes music video: https://youtu.be/uZ8Jy1xgqPU

Oct 06

## Archimedes’ Puzzle

http://illuminations.nctm.org/Lesson.aspx?id=2523 “The Stomachion is an ancient tangram-type puzzle. Believed by some to have been created by Archimedes, it consists of 14 pieces cut from a square. The pieces can be rearranged to form other interesting shapes. In this lesson, students learn about the history of the Stomachion, use the pieces to create other figures, learn about …

May 13

## Nice video on symmetry, music, and art

http://www.ams.org/samplings/math-and-music

Apr 27

## Conic Sections on Desmos

Go to this Desmos graph https://www.desmos.com/calculator/tsfynm2to8 It shows two each of the four conic sections Circles, Ellipses, Hyperbolas, Parabolas Note: A hyperbola has two branches. Only one is shown in the image.  A cone actually has two frustums.  The image only shows one frustum.   http://www.intmath.com/plane-analytic-geometry/conic-sections-summary-interactive.php

Apr 20

## Why the Area of a Trapezoid is What it is

There are six ways to show that the area of a trapezoid is See the following PowerPoint file:TrapezoidArea6Ways

Mar 23

## Spotting Numbers and Visual Patterns

Here a two great websites that provide lots of great pattern problems. [this website hasn’t been functional lately – too bad! – Spotting Numbers – interactive, does require Java.] Visual Patterns – less interactive, (no Java needed). These patterns can be used with elementary students (if you just ask number questions) through advanced algebra (if …