Scale and Proportional Figures

Front

What is a scale factor?

Back

A scale factor is a number that scales, or multiplies, some quantity. In geometry, it is the ratio of the lengths of two corresponding sides of similar figures.

Front

What does it mean for two figures to be similar?

Back

Two figures are similar if they have the same shape but not necessarily the same size. Their corresponding angles are equal, and their corresponding sides are in proportion.

Front

If the scale factor is greater than 1, what type of dilation occurs?

Back

Enlargement.

Front

If the scale factor is less than 1, what type of dilation occurs?

Back

Reduction.

Front

What is the scale factor if a figure is enlarged from a size of 3 to a size of 6?

Back

The scale factor is 2.

Front

What is the scale factor if a figure is reduced from a size of 8 to a size of 2?

Back

The scale factor is 0.25.

Front

How do you find the missing side of similar figures?

Back

Use the ratio of the corresponding sides and set up a proportion to solve for the missing side.

Front

What is the formula for finding the area of similar figures?

Back

The area of similar figures is proportional to the square of the scale factor.

Front

If two similar triangles have a scale factor of 3, how does their area compare?

Back

The area of the larger triangle is 9 times the area of the smaller triangle (3^2 = 9).

Front

What is the relationship between the corresponding angles of similar figures?

Back

The corresponding angles of similar figures are equal.