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Unit Plan
Math Open Reference

Math Open Reference: Triangles

For Students 9th - 10th Standards
A complete reference guide to types of triangles and triangle perimeter and area. It provides definitions and interactive animated activities that enhance further explanation.
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Whiteboard
ClassFlow

Class Flow: Classifying Triangles

For Teachers 5th - 8th Standards
[Free Registration/Login Required] This lesson covers methods of classifying triangles, both according to the length of their sides and by the measure of their interior angle.
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Unit Plan
CK-12 Foundation

Ck 12: Trigonometry: Pythagorean Theorem to Classify Triangles

For Students 10th - 12th Standards
[Free Registration/Login may be required to access all resource tools.] Use the Pythagorean Theorem to determine if triangles are acute, obtuse, or right triangles.
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Unit Plan
Khan Academy

Khan Academy: Identify Triangles by Angles

For Students 3rd - 5th Standards
Practice identifying triangles by their angles as acute, right, or obtuse. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
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Whiteboard
ClassFlow

Class Flow: Angle This Way

For Teachers 3rd - 5th Standards
[Free Registration/Login Required] Students will identify right, acute and obtuse triangles using many interactive tools available in ACTIVstudio 3.0. Students will be engaged using a magnifier tool, the fill tool, and drag and drop and...
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Interactive
Doina Popovici

Math Play: Classifying Triangles

For Students 4th - 6th Standards
Practice identifying triangles as either acute, right, or obtuse in this interactive game.
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Lesson Plan
Illustrative Mathematics

Illustrative Mathematics: G Co Classifying Triangles

For Teachers 9th - 10th Standards
The goal of this task is to help students synthesize their knowledge of triangles where only two of the vertices have been given. They will need to know that a triangle inscribed in a circle, with a diameter of the circle as one side, is...
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Handout
Oswego City School District

Regents Exam Prep Center: Geometry Vocabulary Resources

For Students 9th - 10th
A list of geometry definitions and a matching activity.
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Handout
University of Georgia

University of Georgia: Inter Math: Oblique

For Students 6th - 8th
This site describes the concept of oblique, expressing both triangles and three dimensional solids. Be sure to use the links to related terms, everyday examples, challenging problems, more information, and the interactive check point...
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Unit Plan
CK-12 Foundation

Ck 12: Converse of the Pythagorean Theorem

For Students 7th - 9th Standards
[Free Registration/Login may be required to access all resource tools.] Learn about the converse of the Pythagorean Theorem and some of its applications. Also explains how to identify acute and obutse triangles through the use of the...
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Activity
Texas Instruments

Texas Instruments: Try Angle?

For Teachers 6th - 8th Standards
In this activity, students investigate properties of triangles by randomly generating possible side lengths for triangles. They learn to determine if three line segments can form a triangle. They also learn to classify triangles as...
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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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Activity
University of Saskatchewan (Canada)

University of Saskatchewan: Trigonometric Functions

For Students 9th - 10th Standards
This site examines the six trigonometric functions from a right triangle point of view. Provides information, examples, and lots of exercises for understanding.
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Primary
Windstream

Ojk's Precalculus Study Page: The Law of Cosines

For Students 9th - 10th Standards
An introduction to solving acute and obtuse triangles by using the law of cosines, including a derivation of the formula. Includes several pistures and examples.
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Activity
Beacon Learning Center

Beacon Learning Center: Anglemania!

For Students 3rd - 5th Standards
Students explore four types of angles in this interactive web lesson.
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Handout
Wolfram Research

Wolfram Math World: Cut the Knot! Angles

For Students 9th - 10th Standards
Very good site with links to reviews of various angles.
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Activity
Windstream

Ojk's Precalculus Study Page: The Law of Sines

For Students 9th - 10th Standards
An introduction to solving acute and obtuse triangles by using the law of sines, including a derivation of the formula. Includes several pictures and examples.
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Handout
The Math League

The Math League: Figures and Polygons

For Students 3rd - 8th Standards
This website has basic definitions for most polygons, regular and irregular.
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Interactive
Quia

Quia: Geometric Terms Word Search

For Students 3rd - 8th
Do you need practice remembering or learning different geometry vocabulary words and definitions? This word search is the web site for you! There is a link to a list of terms with definitions you can click if you want to see if you are...
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Professional Doc
Louisiana Department of Education

Louisiana Doe: Louisiana Believes: Eureka Math Parent Guide: Angle Measure and Plane Figures

For Students 4th Standards
A guide to support parents as they work with their students in angle measure and plane figures.