Scale Factor of Similar Shapes

Triangle ABC and XYZ are similar, ABC is the copy and XYZ is the original shape.  What is the scale factor or multiplier used to make the the smaller one larger?

• 2

• ½

• ⅖

• 5/2

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

The pair of figures are similar. Find the missing side.

• x = 9

• x = 28

• x = 7

• x = 63

Find the missing side of the large triangle, then, find the PERIMETER of the large triangle.

• the missing side is 12, the perimeter is 24

• the missing side is 12, the perimeter is 36

The pair of figures is similar. Find the missing side.

• x = 10

• x = 4

• x = 2

• x = 5

The triangles are similar, solve for the question mark.

• 8

• 12.5

• 18

• 24

Sides in similar figures must be proportional.  

• True

• False 

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

Jamie made a scale drawing of his apartment building.  The building is 300 ft tall.  He wants his scale to be 1 inch : 10 ft.  How tall should his building be in his scale drawing?

• 25 inches

• 60 inches

• 1/30 inch

• 30 inches

A large American flag measures 225 feet wide. In an advertisement for renting this flag, the image of the flag is 4 inches wide. What is the scale factor?

• 675

• 56.25

• 65