Science and Mathematics Initiative for Learning Enhancement (SMILE)
Smile: Polyhedrons
This in-depth paper examines the idea of convexity. Euclid's Elements, the first geometry textbook, assumed convexity without mentioning the term.
The Math League
The Math League: Figures and Polygons: Nonagons
This site provides definitions and examples of the various types of polygons including nonagons.
Other
Mathematics Internet Library: Free Internet Books
Practice problem worksheets are available for students needing to study basic terms relating to triangles and other math concepts.
Other
Ic Teachers: Shapes: Triangles
Are you looking for a very basic website that will explain the basic properties of a triangle? Use this site to learn about the properties of equilateral triangles, isosceles triangles, right triangles,and scalene triangles. There are...
Sophia Learning
Sophia: Scalene, Isosceles, and Equilateral Triangles: Lesson 1
This lesson will define scalene, isosceles, and equilateral triangles. It is 1 of 5 in the series titled "Scalene, Isosceles, and Equilateral Triangles."
Free Math Help
Free Math Help: Isosceles Triangles
Students learn about isosceles triangles. The tutorial consists of definitions and sample exercises with solutions.
Free Math Help
Free Math Help: Classification of Polygons and Triangles
The Geometry session explores the classification of polygons and triangles. Definitions and examples are included.
ClassFlow
Class Flow: Braun Polygons
[Free Registration/Login Required] This flipchart is a simple diagram showing the sides and triangles in a polygon.
Shmoop University
Shmoop: Basic Geometry: Triangles
The geometry resource explores triangles. Descriptions, examples, and practice exercises are included.
Shmoop University
Shmoop: Basic Geometry: Area (Polygon, Triangle, Circle, Square)
The geometry resource investigates the area of polygons, triangles, circles, and squares. Formulas and examples are included.
National Council of Teachers of Mathematics
The Math Forum: Problems Library Geometry Triangles
This site contains a wealth of problems that deal with the basic definitions of medians, altitudes, angle bisectors, and perpendicular bisectors or the defining characteristics of the different types of triangles. There are also...
Ducksters
Ducksters: Kids Math: Triangles
Learn about equilateral, right angle, and isosceles triangles on this site. Learn how they work, terms, tricks and examples. .
Calculator Soup
Calculator Soup: Isosceles Triangles Calculator
Use this calculator to find the sides, perimeter, area, semiperimeter, and altitude of an isosceles triangle.
Calculator Soup
Calculator Soup: Regular Polygon Calculator
Use this calculator to calculate properties of a regular polygon. Enter any 1 variable plus the number of sides or the polygon name. Calculates side length, inradius, circumradius, area, and perimeter.
Calculator Soup
Calculator Soup: Equilateral Triangles Calculator
An equilateral triangle is a special case of a triangle where all 3 sides have equal length and all 3 angles are equal to 60 degrees.
Geometry Help
Geometry Help: Pentagons and Hexagons
Explains the basic concept of pentagons and hexagons with step-by-step instructions and methods for solving specific problems on your own relating to this topic.