CK-12 Geometry-Concepts

http://www.ck12.org Chapter 7. Similarity

7.4 AA Similarity

Here you’ll learn how to determine whether or not two triangles are similar using AA Similarity.

What if you were given a pair of triangles and the angle measures for two of their angles? How could you use this
information to determine if the two triangles are similar? After completing this Concept, you’ll be able to use AA
Similarity to decide if two triangles are similar.

Watch This

MEDIA

Click image to the left for use the URL below.

URL: http://www.ck12.org/flx/render/embeddedobject/52546

CK-12 Foundation: Chapter7AASimilarityA

Watch this video beginning at the 2:09 mark.

MEDIA

Click image to the left for use the URL below.

URL: http://www.ck12.org/flx/render/embeddedobject/1302

James Sousa: Similar Triangles

MEDIA

Click image to the left for use the URL below.

URL: http://www.ck12.org/flx/render/embeddedobject/1357

James Sousa: Similar Triangles by AA

Guidance

The Third Angle Theorem states if two angles are congruent to two angles in another triangle, the third angles
are congruent too. Because a triangle has 180◦, the third angle in any triangle is 180◦minus the other two angle
measures. Let’s investigate what happens when two different triangles have the same angle measures.