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Activity
National Council of Teachers of Mathematics

The Math Forum: Problems Library Geometry Triangles

For Students 9th - 10th Standards
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...
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eBook
CK-12 Foundation

Ck 12: Interactive Geometry: 4.4 Theorems About Triangles

For Students 9th - 10th Standards
Discover some theorems about triangles.
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Handout
Oswego City School District

Regents Exam Prep Center: Triangle Information

For Students 6th - 8th Standards
This Oswego City School District site from the Regents Exam Prep Center provides an explanation of the classifications of triangles both by sides and by angles. Pictures are also included.
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Activity
Other

Ic Teachers: Shapes: Triangles

For Students 6th - 9th Standards
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...
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Unit Plan
Cuemath

Cuemath: Right Angled Triangle

For Students 9th - 10th Standards
Explore and learn about the features and properties of a right triangle in this lesson. Includes examples and practice questions.
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Handout
CK-12 Foundation

Ck 12: Geometry: Special Right Triangles Study Guide

For Students 9th - 10th Standards
[Free Registration/Login may be required to access all resource tools.] Different types of right triangles and trigonometric ratios for special right triangles are covered in this study guide.
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Handout
CK-12 Foundation

Ck 12: Geometry: Bisectors, Medians, Altitudes Study Guide

For Students 9th - 10th
This study guide on bisectors, medians, and altitudes covers key vocabulary, different theorems, and facts about the altitude and triangles. It is available for download with free registration.
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Interactive
Math Is Fun

Math Is Fun: Interactive Triangles

For Students 9th - 10th Standards
This is an excellent tool for students to explore how changes in the size of a triangle's sides or angles affect its appearance. Different types of triangles and angles are presented.
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eBook
Math Planet

Math Planet: Pre Algebra: Triangles

For Students 9th - 10th Standards
Learn about the types of triangles by taking a look at an example and a video lesson.
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Unit Plan
CK-12 Foundation

Ck 12: Trigonometry: Lengths of Sides in Isosceles Right Triangles

For Students 10th - 12th Standards
[Free Registration/Login may be required to access all resource tools.] Here you'll learn what an isosceles right triangle is, the relationships between the sides of an isosceles right triangle, and how to find the length of an unknown...
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Lesson Plan
Alabama Learning Exchange

Alex: Tan Ii

For Teachers K - 1st Standards
The Chinese character mark for Tan II (pronounced she-tow-bah) is the second of two lessons to introduce first grade learners to geometry using tangrams. This instructional activity incorporates history, math, and language arts. In this...
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Activity
Maths Challenge

Maths challenge.net: Perpendicular Construction

For Students 9th - 10th Standards
This is a "three star" geometry problem where prior math problem skills and proof experience is recommended to solve this "Perpendicular Construction" problem.
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Activity
Homeschool Math

Homeschool Math: Equilateral, Isosceles, and Scalene Triangles

For Students 4th - 6th
This geometry lesson defines equilateral, isosceles, and scalene triangles, and has a variety of exercises, including drawing exercises.
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Whiteboard
ClassFlow

Class Flow: Triangles

For Teachers 3rd - 8th Standards
[Free Registration/Login Required] Using this flipchart students learn to recognize and classify different triangles, including equilateral, isosceles and scalene. The teacher will use this lesson plan to review different types of...
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Lesson Plan
Alabama Learning Exchange

Alex: "Tan"

For Teachers K - 1st Standards
The Chinese character mark formerly known as "Tan" is the first of two lessons to introduce first grade students to geometry using tangrams. This lesson plan incorporates history, math, and language arts. In this lesson plan students...
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Handout
The Math League

The Math League: Figures and Polygons

For Students 9th - 10th Standards
This site provides definitions of different types of polygons and figures.
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Lesson Plan
Science Buddies

Science Buddies: Tiling With Spidrons

For Teachers 9th - 10th
If art and math are both passions of yours, this project is meant for you! Spidrons are geometric forms made from alternating sequences of equilateral and isosceles (30 degrees, 30 degrees, 120 degrees) triangles. Spidrons were...
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Activity
Rice University

Rice University: Cynthia Lanius: Hidden Polygon Activity

For Students 4th - 7th Standards
On this site students are instructed to locate different types of polygons on triangle grid paper. This page can be printed so that students can actually draw them. It also gives a definitions link for each polygon.