Two sets of congruent angles leads to three. Using diagrams of two triangles, the presentation intuitively shows that if two sets of angles are congruent, the third set is too. The portion of a geometry playlist uses that information to show that it takes only two sets of congruent angles to prove two triangles are similar.

Concepts

similar triangles, similarity, triangles, corresponding angles, corresponding sides

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Additional Tags

math

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Instructional Ideas

• Develop an informal proof of AA Similarity

Classroom Considerations

• Individuals should know how to identify correspondence in similar triangles
• Assumes students are familiar with the sum of the angles of a triangle

• This video is hosted on YouTube

Pros

• Contains a link to other CK-12 resources on AA
• Works examples related to determining two triangles are similar

Cons

• None

Common Core

8.G.A.5 HSG-SRT.A.2 HSG-SRT.A.3 MP2 MP3