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Activity
Texas Instruments

Texas Instruments: Angle Sum in Triangles Proof: Rotation and a Parallel Line

For Teachers 9th - 10th Standards
This investigation uses Cabri Jr. and a cleaver rotation of a triangle to "prove" that the angles in a triangle add up to 180. This could be used to reinforce triangles and paralled lines as well as introduce the concept of rotating an...
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Activity
Government of Alberta

Learn Alberta: Math Interactives: Exploring Angles Within a Triangle

For Students 6th - 8th
This multimedia Learn Alberta math resource looks at angles of a triangle in the context of building bikes and choosing bike sizes. The accompanying interactive component lets students explore build different sized triangles while...
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Unit Plan
CK-12 Foundation

Ck 12: Elem Math: Determining the Unknown Angle in a Triangle

For Students 3rd - 5th Standards
[Free Registration/Login may be required to access all resource tools.] Students watch a video and attempt practice problems on how to determine a missing angle in a triangle.
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Activity
Texas Instruments

Texas Instruments: Sum of Interior Angles in a Triangle With Cabri Jr.

For Teachers 9th - 10th
Students will discover the sum of the interior angles in a triangle using the Cabri Jr. Application.
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Activity
Texas Instruments

Texas Instruments: Angles of a Triangle

For Teachers 9th - 10th
In this activity, students investigate the sum of the measures of the interior angles of a triangle. They will explore interior angles, and their relationship with the exterior angles of a triangle.
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Interactive
Mangahigh

Mangahigh: Shape: Proof of the Sum of the Angles in a Triangle

For Students 9th - 10th Standards
Determine that all angles in a triangle equal 180 degrees.
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Lesson Plan
Oswego City School District

Regents Exam Prep Center: Angles and Triangles

For Teachers 9th - 10th Standards
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...
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Unit Plan
CK-12 Foundation

Ck 12: Geometry: Comparing Angles and Sides in Triangles

For Students 9th - 10th Standards
[Free Registration/Login may be required to access all resource tools.] This concept teaches students the relationship between opposite angles and sides in triangles and how to use this relationship to compare triangles. students examine...
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Unit Plan
CK-12 Foundation

Ck 12: Geometry: Triangle Sum Theorem Grade 8

For Students 8th
[Free Registration/Login may be required to access all resource tools.] Finding and understanding the angle measures of triangles.
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Unit Plan
CK-12 Foundation

Ck 12: Geometry: Triangle Sum Theorem Grade 7

For Students 7th
[Free Registration/Login may be required to access all resource tools.] Recognize the sum of the interior angles of a triangle as 180 degrees.
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Unit Plan
CK-12 Foundation

Ck 12: Geometry: Exterior Angles Theorems

For Students 9th - 10th Standards
[Free Registration/Login may be required to access all resource tools.] This concept teaches students the sum of exterior angles for any polygon and the relationship between exterior angles and remote interior angles in a triangle....
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Activity
Texas Instruments

Texas Instruments: Extension: Parallel Lines and the Sum of the Angles

For Teachers 6th - 8th Standards
Students construct a line parallel to the base of a triangle and measure the angles formed. They use the construction to prove that the sum of the measures of the interior angles of a triangle is 180 degrees.
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Activity
AAA Math

Aaa Math: Finding the Third Angle of a Triangle

For Students 9th - 10th Standards
Finding the third angle of a triangle becomes easier by the explanation and examples presented.
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Activity
Varsity Tutors

Varsity Tutors: Hotmath: Algebra Review: Angle Sum Theorem

For Students 9th - 10th
Find a quick, concise explanation of the Angle Sum Theorem. A step by step explanation of the proof is included to help you understand the theorem.
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Unit Plan
CK-12 Foundation

Ck 12: Geometry: Triangle Sum Theorem Grades 8 10

For Students 9th - 10th
[Free Registration/Login may be required to access all resource tools.] Recognize the sum of the interior angles of a triangle as 180 degrees.
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Unit Plan
CK-12 Foundation

Ck 12: Triangle Sum Theorem

For Students 6th - 9th
[Free Registration/Login Required] Students explore the concept of the triangle sum theorem by navigating through the interactive learning module and then answering questions that go along with the module. Students can also learn more...
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Unit Plan
CK-12 Foundation

Ck 12: Geometry: Angle Measures in Given Triangles

For Students 6th
[Free Registration/Login may be required to access all resource tools.] Find the degree measure of an unknown angle in given triangles.
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Unit Plan
CK-12 Foundation

Ck 12: Triangle Sum Theorem

For Students 9th - 10th
[Free Registration/Login Required] Students explore the concept of the triangle sum theorem by navigating through the interactive learning module and then answering questions that go along with the module. Students can also learn more...
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Unit Plan
CK-12 Foundation

Ck 12: Elem Math: Determine Unknown Angles: Isosceles, Scalene, Right Triangles

For Students 3rd - 5th Standards
[Free Registration/Login may be required to access all resource tools.] Students watch a video and attempt practice problems on finding the missing angles in triangles.
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Unit Plan
CK-12 Foundation

Ck 12: Geometry: Triangle Sum Theorem Grades 9 10

For Students 9th - 10th
[Free Registration/Login may be required to access all resource tools.] This concept teaches students the Triangle Sum Theorem, and how to use it.
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Handout
Khan Academy

Khan Academy: Triangle Angles Review

For Students 9th - 10th Standards
Reviews the rule that the interior angles of a triangle always add up to 180 degrees. Includes three practice problems.
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Interactive
Walter Fendt

Walter Fendt: Sum of Angles in a Triangle

For Students 9th - 10th
A short interactive activity to show that the sum of the angles of a triangle is 180 degrees.
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Unknown Type
Khan Academy

Khan Academy: Find Angles in Triangles

For Students 7th - 8th Standards
Find missing angle measures using the properties of triangles. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video, or receive hints.
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Activity
Texas Instruments

Texas Instruments: Measuring Angles in a Triangle

For Teachers 9th - 10th Standards
In this activity, students learn about the sum of the angles in a triangle. They understand triangles and their interior angles.