Scale Factor Dilations

The red triangle has been dilated by a scale factor of 1/4 about the origin, which triangle is it's new image?

• green triangle 

• red triangle 

• black triangle

• none of these 

How do you write the algebraic notation when the scale factor is 1/2?

• (x, y) −> (2x, 2y)

• (x, y) −> (1/2x, 1/2y)

• (x, y) −> (-2x, -2y)

• (x, y) −> (2x, 1/2y)

The two polygons are similar.

Find the value of x

Find the scale factor

Find the ratio of the perimeter.

Value of x: ____, Scale factor: ____, Ratio of perimeter: ____

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If the scale factor is less than one, the new figure will be

• an enlargement

• a reduction

• a scale factor

• bigger

If the scale factor is greater than one, the new figure will be

• reduction

• enlargement

• scale

• not proportional

Which of the following is the algebraic representation for a dilation?

• (x, y) → (x, 3y)

• (x, y) → (3x, 3y)

• (x, y) → (x, y - 3)

• (x, y) → (.5x, .4y)

Are the two polygons similar? If not, explain why. (They are not drawn to scale, but you can assume all angles are 90°.)

• Yes

• No; Not enough information to tell

• No; 5 ⁄ 25 ≠ 6 ⁄ 10

• No; 5 ⁄ 25 ≠ 8 ⁄ 41

Find the scale factor of the dilation. Then tell whether the dilation is a reduction or an enlargement.

• 2 / 5; reduction

• 5 / 2; enlargement

• 2 / 3; reduction

• 3 / 2; enlargement

If two polygons are SIMILAR, then the corresponding sides must be _____.

• Congruent

• Proportional

• Parallel

• similar

Describe the similarity transformation that maps to (dilations have a center at the origin).

• a dilation with a scale factor of 2 followed by a translation 4 units right and 3 units down.

• a dilation with a scale factor of 1 / 2 followed by a translation 4 units left and 3 units up.

• Translation 4 units right and 3 units down followed by a dilation with a scale factor 2.

• Translation 4 units left and 3 units up followed by a dilation with a scale factor 1 / 2.