More Applications of Proportions

SIMILAR FIGURES

Recall

A ratio is a comparison between two quantities Ex. 20 gallons to 150 miles -> 20/150

a proportion is two ratios that are equivalent Ex. 2/4 = 6/12 (both ratios represent half!)

What is a proportion?

A. B. C. D.

25% 25%25%25%

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15

A. A comparison between two quantities

B. Two ratios that are equivalent

C. Two things that are always the same size

D. A portion

Similar Figures

Two figures are similar if they are the same shape, but different size.

The ratios of their sides form a proportion. Which of the rectangles here are similar?

How can you tell?

Solving for a missing side

Step 1: set up a proportion using corresponding sides, but make sure you set them up in the same order!!!

Step 2: Cross multiply and divide to find the missing side.

Solve for the missing side below.

A. B. C. D. E.

20% 20% 20%20%20%

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50

A. 3B. 4C. 5.5D. 2.6E. 1.5

Solve for the missing side.

A. B. C. D.

25% 25%25%25%

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50

A. 304 cmB. 300 cmC. 250 cmD. 290 cm

Imagine Someone Made a Statue of You….

If we want the statue to be 114 ft tall and proportionate to you, how wide should it be?

STATUE OF YOU ACTIVITY Choose a partner

Measure each other’s height, shoulder width, and foot length. Record your measurements on the handout.

Figure out the proportions of your statue/figurine (problems on back)