Similar Figures, find scale factor and solve for missing sides

Multiple Choice

Two objects that are the same shape but not the same size are _______.

• Congruent
• Vertical
• Similar
• Complementary 

scale factor -  is the ratio between corresponding measurements of an object and a representation of that object

​Reduction. Scale factor is a fraction between 0 and 1. (divided by 2 = times 1/2)

Poll

Find the scale factor of the enlargement from Y to X

• 1/2

• 3

• 2

• 4

Multiple Choice

Find the scale factor of the reduction from C to A

• 2

• 1/2

• 3

• 1/3

Multiple Choice

What is the scale factor from ΔDEF to ΔABC?

• 1/2
• 7/3
• 2
• 10/3

EXPLANATION

The second triangle listed is 3 times as large. If you use the ratios, 27/9 = 3 and 21/7 = 3. The second triangle listed is larger, so the scale factor is larger than 1.

Poll

The triangles below are similar.  What is the scale factor of the REDUCTION of triangle DEF to triangle ABC?

• 2

• 3

• $$\frac{1}{3}$$

• $$\frac{1}{2}$$

EXPLANATION

This time, the second triangle listed is smaller so the scale factor is smaller than 1. You can use the reciprocal of the answer you got from the previous problem or use the ratios. Make sure to put the smaller number on top if you find the ratios: 9/27 and 7/21 both reduce to 1/3.

Poll

The triangles below are similar.  What is the scale factor of triangle DEF to triangle ABC?

• 2

• 3

• $$\frac{1}{3}$$

• $$\frac{1}{2}$$

Multiple Choice

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

• x = 10
• x = 4
• x = 2
• x = 5

Multiple Choice

Find missing side

• 5
• 7
• 9
• 11

Multiple Choice

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

• x = 12
• x = 3
• x = 40
• x = 4

Multiple Choice

The two rectangles are scale drawings. What is the measurement of x?

• 21
• 1.25
• 20
• 4

Multiple Choice

Find side length X.

• 30
• 25
• 15
• 40

Multiple Choice

Solve for x.

• 2

• 7

• 0.5

• 12

Poll

In a proportion the numbers diagonally across from each other are multiplied together.

• Cross Products
• Unit Rate
• Rate
• Scale Drawing

Multiple Choice

An equation stating that two ratios are equal.

• Proportion
• Congruent
• Unit RAte
• Scale FActor