University of Georgia
University of Georgia: An Elementary Application of Similar Triangles
Excellent review site on similar triangles. Includes diagrams and explanation of application.
Wolfram Research
Wolfram Math World: Triangles
This site provides detailed overviews of many of the concepts and theorems associated with triangles. Content focuses on general triangles, cevians, triangle centers, triangle circles, and triangle lines.
National Council of Teachers of Mathematics
The Math Forum: Triangle Formulas
Investigate the geometric definitions of triangles, focusing upon equilateral, isosceles, right, and scalene with detailed drawings and appropriate formulas for each. This site has links to more information on triangles.
Oswego City School District
Regents Exam Prep Center: Angles and Triangles
On this site a viewer can learn about the different types of triangles, and categorized by either angles or sides. Tutorials are also included for interior and exterior angles of triangles. A teacher resource page includes a lesson plan...
Oswego City School District
Regents Exam Prep Center: Mid Segment of a Triangle
Three resources to help you plan instruction on the mid-segment of a triangle: a lesson with definition, properties, and examples of a mid-segment of a triangle; a seven-question quiz through which students can practice working with...
Shodor Education Foundation
Shodor Interactivate: Triangle Explorer
This applet allows users to study the nature of triangles and their area. It draws random triangles on a Cartesian coordinate system. The user can determine the area of the triangle using his or her preferred method. After the calculated...
Mathigon
Mathigon: Geometry: Polygons and Polyhedra: Polygons
This lesson focuses on polygons; a polygon is a closed, flat shape that has only straight sides. Polygons can have any number of sides and angles, but the sides cannot be curved.
University of Georgia
University of Georgia: Inter Math: Recommended Investigations of the Triangle
Investigate the qualities of a triangle with these seventeen word problems. Many include ways to extend the lesson.
Math Open Reference
Math Open Reference: Constructions
Learn about drawing shapes using only a compass and straight edge or ruler with out measuring any lengths or angles.
Better Lesson
Better Lesson: Goody Goody Gumdrop! Building Structures Are Fun!
In this lesson, the children will be building a physical model to illustrate how the shape of an object, such as triangles, helps it function. At the end, the children will test their gumdrop structures and the class will collectively...
Math Drills
Math Drills: Geometry Worksheets
Download these worksheets to sharpen your geometry skills. Sheets focus on angles, coordinate geometry, triangles, quadrilaterals, transformations, and three-dimensional geometry, and more.
Cuemath
Cuemath: Angle Bisector Theorem
This short lesson focuses more on the angle bisector theorem. Learn about the angle bisector theorem proof, triangle angle bisector theorem, how to construct angle bisector, and other interesting properties and facts around angle bisectors.
Cuemath
Cuemath: Law of Cosine
Explore the world of the Law of Cosine in this mini-lesson. Provides a definition, simulations, examples, and practice questions that help with understanding.
Cuemath
Cuemath: Pythagoras Theorem
In this lesson, you will learn about the Pythagoras theorem, its derivations, and equations followed by solved real-world problems on the Pythagoras theorem triangle and squares.
Cuemath
Cuemath: Exterior Angle Theorem
Explore the exterior angle theorem using the simulator and try your hand at solving the interactive questions at the end.
Cuemath
Cuemath: Acute Triangle
Explore the world of acute triangles in this mini-lesson. Explores its properties, how to create it, and other interesting facts related to acute triangles.
Cuemath
Cuemath: Triangles
Explore everything about triangles. Learn about the different types, important properties, and how to find its area and perimeter. Check out the solved examples and interactive questions for better understanding.
Cuemath
Cuemath: Equilateral
Learn all about the basic properties of equilateral. This lesson targets the meaning of equilateral, shows how to construct equilateral shapes, explores some of the equilateral shapes and properties, and how to apply them while solving...
Cuemath
Cuemath: Hypotenuse Leg Theorem
Explore the world of the hypotenuse leg theorem in this mini-lesson. Provides a definition, examples, and practice questions with answers that help with understanding their properties.
Cuemath
Cuemath: Angle Sum Theorem
Explore the world of the angle sum theorem in this mini-lesson. Provides a definition and solved examples that help with understanding their properties. Includes practice questions with answers.
Cuemath
Cuemath: Sine Law
This comprehensive guide explores the topic of sine law, by finding answers to questions like what is the law of sines, what are the applications of sine law, and proof of the sine law. Includes solved examples and practice questions.
OER Commons
Oer Commons: Polygons
Seventh graders find the area of regular polygons, recalling what they already know about the area of geometric shapes and generalizing a formula for any regular polygon.
Math Drills
Math Drills: Measurement Worksheets
Download these free worksheets to sharpen your measurement skills. Sheets focus on temperature, conversion, area and perimeter, volume, and more.
E-learning for Kids
E Learning for Kids: Math: Group of Pyramids: 2 D Shapes
Abeni works at the pyramids. Visit her and find out more about circles and triangles.