Similar Triangles & Proportions

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 scale factor in similar triangles?

Back

The ratio of the lengths of corresponding sides of two similar figures. It indicates how much one figure is enlarged or reduced compared to the other.

Front

What does AA stand for in triangle similarity?

Back

Angle-Angle; a criterion for triangle similarity stating that if two angles of one triangle are equal to two angles of another triangle, the triangles are similar.

Front

What does SSS stand for in triangle similarity?

Back

Side-Side-Side; a criterion for triangle similarity stating that if the lengths of the corresponding sides of two triangles are proportional, the triangles are similar.

Front

What does SAS stand for in triangle similarity?

Back

Side-Angle-Side; a criterion for triangle similarity stating that if two sides of one triangle are proportional to two sides of another triangle and the included angles are equal, the triangles are similar.

Front

How do you find the measure of an angle in a triangle given the ratio of the angles?

Back

To find the measure of an angle, first determine the total parts of the ratio, then divide 180° by the total parts to find the value of one part, and multiply by the number of parts for the angle.

Front

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

Back

The scale factor is 3/2 or 1.5, since 9 cm (DE) divided by 6 cm (AB) equals 1.5.

Front

What is the relationship between the sides of similar triangles?

Back

The lengths of corresponding sides of similar triangles are proportional.

Front

If two triangles have sides in the ratio 2:3, what is the scale factor from the smaller triangle to the larger triangle?

Back

The scale factor is 3/2 or 1.5.

Front

How can you determine if two triangles are not similar?

Back

If the corresponding angles are not equal or the sides are not in proportion, the triangles are not similar.