4-10 Similar Figures and Scale Factor

Front

What are similar figures?

Back

Figures that have the same shape but may have different sizes. Their corresponding angles are equal, and their corresponding sides are in proportion.

Front

What is a scale factor?

Back

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

Front

If the scale factor is less than one, what happens to the figure?

Back

The figure will be a reduction.

Front

What are corresponding sides?

Back

Sides of two or more figures that are in the same position relative to each figure.

Front

How do you find a missing side in similar figures?

Back

Use the scale factor to set up a proportion between the corresponding sides.

Front

If triangle ABC is similar to triangle DEF, and the length of side AB is 5 and side DE is 10, what is the scale factor?

Back

The scale factor is 2.

Front

What is the relationship between corresponding angles in similar figures?

Back

Corresponding angles are equal in measure.

Front

If the scale factor is 3, what happens to the area of the figure?

Back

The area of the figure increases by a factor of 3², or 9.

Front

What is the formula to find the scale factor between two similar figures?

Back

Scale Factor = Length of a side in the new figure / Length of the corresponding side in the original figure.

Front

If two triangles are similar and one has a side length of 6 and the corresponding side in the other triangle is 12, what is the missing side if the other triangle's side is x?

Back

x = 6 * (12/6) = 12.