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### Course: High school geometry>Unit 4

Lesson 2: Introduction to triangle similarity

# Triangle similarity review

Review the triangle similarity criteria and use them to determine similar triangles.

## What are the triangle similarity criteria?

AATwo pairs of corresponding angles are equal
SSSThree pairs of corresponding sides are proportional
SASTwo pairs of corresponding sides are proportional and the corresponding angles between them are equal

Problem 1
Which triangle is similar to triangle $A$?

Want to practice more problems like this? Check out this exercise for the AA criterion and this exercise for the SSS criterion.

## Want to join the conversation?

• i dont get most of this stuff
• Try to practice upon it and you might get it, or just use khan academy's practice a lot. Hope it helps
• How can you tell the difference between SAS and SSA? (Assume you had a problem and had to chose if it was sim. because of SAS or SSA, how would you figure it out?)
• SAS means that the angle is in between the two sides in question. SSA means the angle is not in between.
• The videos im watching is not adding up to the working you guys are giving me. Im so lost.
• Yo, man. This is how we do da thing. Firstly, if the triangles have 2+ matching corresponding angles, then it is similar. If it has side lengths that can be divided by a number, say X, and then match the side lengths of your other triangle, then it is similar. If it has 2 matching corresponding(see last sentence) sides, and the angle between these is the same, then it is similar. -Beauregard42. If this helps you, your welcome.
• Define Equation
• An equation is a statement with an equals sign.

So 3 + 5 = 8 and 5x + 12 = (x / 4) + 3 are both equations,
but 24 * 9 and 3y ≥ x - 8 are not equations.
• What other triangle similarity criteria can be used?
• I believe AA, SAS, and SSS are the only triangle similarity theorems
• i don't get it sometimes