Similar Shapes Match Proportions

What is a scale factor?

• Shapes that have the same shape, but not necessarily the same size.

• A ratio/number that compares the sizes of the parts of the scale drawings.

• They are sides that are in the same position in different plane figures.  

• The length of a side of a similar figure.

Solve for X.

• 2 ft

• 3 ft

• 4 ft

• 6 ft

All corresponding sides are proportional (same ratio) in similar figures.

• True

• False

Find missing side

• 5

• 7

• 9

• 11

Which side length corresponds with EF?

• ML

• LM

• OL

• EH

The rectangles are similar.

Solve for x.

Mathematical Equivalence

ON

Are the two figures similar?

• yes

• no

Tell whether the two figures are similar. Explain your reasoning.

• Yes, similar because they are the same shape and side lengths are proportional.

• No, not similar because they are the same shape, but side lengths are not proportional.

• Yes, same shape

• No, different sizes

Triangle ABC and XYZ are similar.  Use your knowledge of scale factor to find the length of X.

• 20

• 25

• 100

• 40

What is the scale factor of these similar shapes?

• 10

• 7

• 9

• 11