Informal Proof Of Angle-Angle Criterion
An informal proof of the Angle-Angle (AA) criterion for similar triangles and informal arguments as to whether or not triangles are similar based on Angle-Angle criterion, with video lessons, examples and step-by-step solutions for students in Grade 8 and also for SAT/ACT prep.
Related Pages
Similar Triangles
Lesson Plans and Worksheets for Grade 8
Lesson Plans and Worksheets for all Grades
More Lessons for Grade 8
Common Core For Grade 8
New York State Common Core Math Grade 8, Module 3, Lesson 10
Lesson 10 Student Outcomes
- Students know an informal proof of the Angle-Angle (AA) criterion for similar triangles.
- Students present informal arguments as to whether or not triangles are similar based on Angle-Angle criterion.
Lesson 10 Summary
Two triangles are said to be similar if they have two pairs of corresponding angles that are equal.
Classwork
Concept Development
Exercises
- Use a protractor to draw a pair of triangles with two pairs of equal angles. Then measure the lengths of sides, and verify that the lengths of their corresponding sides are equal in ratio.
- Draw a new pair of triangles with two pairs of equal angles. Then measure the lengths of sides, and verify that the lengths of their corresponding sides are equal in ratio.
Examples 1 - 3
Are the triangles shown below similar? Present an informal argument as to why they are or why
they are not.
Exercises 3 - 5
Are the triangles shown below similar? Present an informal argument as to why they are or why
they are not.
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