Using Proportions with Similar Figures

What is true about the shape and size of similar figures?

• Same shape and same size

• Same shape and proportional size

• Different shape and same size

• Different shape and proportional size

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

• Similar because they are the same shape and side measurements are proportional.

• Not similar because they are the same shape, but side measurements are not proportional.

• Similar because they are the same shape.

• Not similar because they are different sizes.

Using a proportion, find the height of the tree.

• 0.0625 ft.

• 36 ft

• 16 ft.

• 12 ft

In the figures below, ∆QSR ~ ∆XYZ. Write a proportion and solve for side QS.

• 2.4

• 15

• 24

• 16

• A
• B
• C
• D

A tree is 12 feet tall and casts a shadow 9 feet long. A building nearby casts a shadow that measures 24 feet. How tall is the building? (Draw a picture, set up a proportion)

• 24 feet

• 21 feet

• 27 feet

• 32 feet

You can decide if two figures are similar by doing what?

• Adding all the sides

• Making proportions

• Looking closely

• Checking with a friend

Sides in similar figures must be proportional.  

• True

• False 

What is the scale factor from triangle ABC to triangle DEF?

• 1:2

• 2:3

• 2:1

• 3:1

Solve for f.

• 6

• 4

• 3

• 8