Similar Figures and Scale Factors

Front

What are similar figures?

Back

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

Front

What is a scale factor?

Back

A number that describes how much a figure is enlarged or reduced. It is the ratio of the lengths of corresponding sides of similar figures.

Front

If a scale factor is 2, what does that mean?

Back

It means the new figure is twice as large as the original figure.

Front

If a scale factor is 1/2, what does that mean?

Back

It means the new figure is half the size of the original figure.

Front

How do you determine if two figures are similar?

Back

Two figures are similar if their corresponding angles are equal and the lengths of their corresponding sides are proportional.

Front

What is the scale factor from a figure measuring 4 units to a figure measuring 8 units?

Back

The scale factor is 2.

Front

What is the scale factor from a figure measuring 10 units to a figure measuring 5 units?

Back

The scale factor is 1/2.

Front

If two triangles have sides measuring 3 cm, 4 cm, and 5 cm, and 6 cm, 8 cm, and 10 cm, are they similar?

Back

Yes, they are similar because the sides are proportional (3:6, 4:8, 5:10).

Front

What does it mean for side lengths to be proportional?

Back

It means the ratios of the lengths of corresponding sides are equal.

Front

If triangle ABC is similar to triangle DEF, and the scale factor is 3, what is the length of a side in triangle DEF if the corresponding side in triangle ABC is 5 cm?

Back

The length of the corresponding side in triangle DEF is 15 cm.