Unit 6: Similarity Quiz #1 Review

What type of transformation is shown in the diagram?

• Translation

• Reflection

• Rotation

• Dilation

Warm-up: What does the scale factor do in a dilation?

• Tells you how much the image grows or shrinks

• Tells you what the center of dilation is

• There's not enough information here to answer this

• Nothing, it's unnecessary information

Which scale factors would increase an image?

• 2

• 5
  

Answer explanation

The Scale Factor must be MORE THAN 1 to shrink a figure

Which scale factors shrink an image?

• 2

Answer explanation

The Scale Factor must be LESS THAN 1 to shrink a figure

Similar figures have ...

• Congruent Angles

• Congruent Side Lengths

• Proportional Angles

• Proportional Side Lengths

Which statements are true about Dilations?

• Corresponding side lengths are CONGRUENT

• Corresponding side lengths are PROPORTIONAL

• Corresponding angles are CONGRUENT

• Corresponding angles are PROPORTIONAL

What is the image of (10, –3) under the dilation with a scale factor of 2?

• (8, -2)
• (15, -9)
• (5, -1)
• (20, -6)

Answer explanation

Multiply each coordinate by the scale factor

In which quadrant would the image of point (-1, –5) fall after a dilation using a scale factor of 4?

• III

• I

• II

• IV

Answer explanation

You multiply each coordinate by the scale factor so the figure would stay in the same quadrant.

The image of point Z, AFTER a dilation of 4, is (12,16).  What is the original coordinate of point Z?

• (15, 20)
• (9, 12)
• (3, 4)
• (6, 8)

Answer explanation

To get back to the original size you have to MULTIPLY by the RECIPROCAL. The Reciprocal of 4 is 1/4.

The point D (3, 2) maps onto D’ (6, 4) under a dilation.  What is the scale factor?

• 4
• 3
• 2
• 5

Answer explanation

Multiple each original coordinate by each answer choice to see which one gives you the prime coordinates. Check BOTH x and y.