Similar Triangles

Front

What are similar triangles?

Back

Triangles that have the same shape but may differ in size. Their corresponding angles are equal, and their corresponding sides are in proportion.

Front

What is the AA criterion for similarity?

Back

If two angles of one triangle are equal to two angles of another triangle, then the triangles are similar.

Front

What is the SSS criterion for similarity?

Back

If the lengths of the corresponding sides of two triangles are in proportion, then the triangles are similar.

Front

What is the SAS criterion for similarity?

Back

If two sides of one triangle are in proportion to two sides of another triangle and the included angles are equal, then the triangles are similar.

Front

How do you find the length of a side in similar triangles?

Back

Use the proportion of the corresponding sides. If triangle ABC is similar to triangle DEF, then AB/DE = AC/DF.

Front

If two triangles are similar, what can be said about their perimeters?

Back

The ratio of their perimeters is equal to the ratio of their corresponding sides.

Front

What is a scale factor in similar triangles?

Back

The ratio of the lengths of corresponding sides of two similar triangles.

Front

How do you solve for a missing side in similar triangles?

Back

Set up a proportion using the lengths of the corresponding sides and solve for the unknown.

Front

If triangle ABC is similar to triangle DEF and AB = 6, DE = 9, what is the scale factor?

Back

The scale factor is 6/9 or 2/3.

Front

What is the relationship between the areas of similar triangles?

Back

The ratio of the areas of two similar triangles is equal to the square of the ratio of their corresponding sides.