Finding Missing Side Similar Figures

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

• x = 12

• x = 3

• x = 40

• x = 4

Are these triangles similar?

• Yes

• No

Find the missing perimeter.

• 15

• 20

• 25

• 30

Tell whether the two figures are similar. Explain your reasoning. (Hint: are they proportional?)

• 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

Match the following similar figures to the correct missing side lengths.

(hint: use proportions to find the value of each variable)

• x=8

• 
• x=25

• 
• y=20

• 
• x=4

• 
• x=0.66666

• 

The following figures are similar. Use proportions to find the value of x.

ONLY FIND x!!

Mathematical Equivalence

ON

The following figures are similar. Use proportions to find the value of y.

ONLY FIND y!!

Mathematical Equivalence

ON

Determine the scale factor of the similar figures:

​ (a)  

• 2:5

• 6:15

• 10:25

• 8:20

• 5:2

• 15:6

• 25:10

• 20:8

Determine the scale factor of the similar figures:

​ (a)  

• 1:2

• 2:4

• 3:6

• 2:1

• 4:2

• 6:3

• 2:3

• 4:6

Determine the scale factor of the similar figures:

​ (a)  

• 4:3

• 3:4

• 20:15

• 15:20