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## High school geometry

### Course: High school geometry > Unit 4

Lesson 2: Introduction to triangle similarity- Intro to triangle similarity
- Triangle similarity postulates/criteria
- Angle-angle triangle similarity criterion
- Determine similar triangles: Angles
- Determine similar triangles: SSS
- Determining similar triangles
- Prove triangle similarity
- Triangle similarity review

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# Triangle similarity review

CCSS.Math:

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

## What are the triangle similarity criteria?

AA | Two pairs of corresponding angles are equal | |

SSS | Three pairs of corresponding sides are proportional | |

SAS | Two pairs of corresponding sides are proportional and the corresponding angles between them are equal |

*Want to learn more about the triangle similarity criteria? Check out this video.*

## Check your understanding

*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(15 votes)
- Try to practice upon it and you might get it, or just use khan academy's practice a lot. Hope it helps(13 votes)

- 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?)(8 votes)
- SAS means that the angle is in between the two sides in question. SSA means the angle is not in between.(12 votes)

- The videos im watching is not adding up to the working you guys are giving me. Im so lost.(6 votes)
- 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.(8 votes)

- why does this make sense(4 votes)
- Because it just does.(0 votes)

- What other triangle similarity criteria can be used?(1 vote)
- gelp im in 8 doing this while other people are doing calculus rn :sob:(1 vote)
- 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.(0 votes)
- These lessons do not explain SSS similar triangles very well. What lesson would help me understand the basics?(0 votes)
- I suppose trying the Triangle Similarity postulates/criteria lesson, or going back and reading the articles and doing all of the practice problems may help you. Ultimately, in summary, the SSS similarity is used when every side can be multiplied by a constant to get the new side, for example, if AB/XY was 4, AC/AZ was 4, and BC/YZ was 4, it would be a SSS similarity because each value can be multiplied either by 4 or 1/4 (depending on which number is larger) which is defined as the constant. I hope this helps!(1 vote)

- SSS is congruent to ASA because they all have side, angel side.

Perhaps there's another way to connect angel side angel with each other.

LOL its funny because both triangles are similar to triangle A.

How should we know if they do connect? We dont know yet how triangles are similar with each other.(0 votes)