Dilations and Similar Figures Review

Dilations and Similar Figures Review

Dilations

• Increases(enlarge) or decreases(shrink) the size of a figure.

• Maintains the same shape, though size will change.

• Enlarges or shrinks depending on the scale factor.

• Scale factor must be greater than 1 to produce an enlargement

• Scale factor must be between 0 and 1 to produce a shrinked figure.

Scale Factor

• Value that is multiplied by side measures of a figure to produce a dilation.

• If on the coordinate plane, the value is multiplied by the x-andy-coordiantes.

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Scale Factor

Written as a ratio of corresponding side measures.

Multiple Choice

Which if the following is true about dilations?

• causes an enlargement of figures

• Causes a reflections

• Causes figures to be congruent.

• Causes a figure to move up or down.

Multiple Choice

A scale factor is

• Divided by corresponding side measures

• Added to side measures

• Multiplied to side measures

• Subtracted by side measures

Multiple Choice

A figure is enlarged when

• The scale factor is less than 1

• The scale factor is greater than 1

• The scale factor is equal to 1

• There is no scale factor.

Multiple Choice

A figure shrinks when

• The scale factor is greater than 1

• The scale factor is less than 1

• The scale factor is less than 0

• The scale factor is between 0 and 1.

Multiple Choice

A triangle with coordinates D(-2, 3), E(-4, 7), and F( 0, 5) is dilated by a scale factor of 2. What are the new coordinates?

• D'(0, 5), E'(-2, 12), F'(2, 7)

• D'(2, 3), E'(-4, 7), F'(0, 5)

• D'(-4, 6), E'(-8, 14), F'(0, 10)

• D'(3, -2), E'(7, -4), F'(5, 0)

Similar Figures

• Corresponding angles are congruent

• Corresponding sides a proportional

Missing Side Measures

• Missing side measures of similar figures can be found by writing a proportion and solving for the missing value.

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Multiple Choice

Find the measures of x and y.

• x = 9m, y = 30m

• x = 3m, y = 9 m

• x = 30 m, y = 9 m

• x = 15 m, y = 30 m

Multiple Choice

Find the measures of x and y.

• x = 14 cm, y = 28 cm

• x = 13 cm, y = 27 cm

• x = 15 cm, y = 30 cm

• x = 10 cm, y y = 18 cm

Multiple Choice

Determine the distance across the river.

• 24 feet

• 72 feet

• 30 feet

• 48 feet

Multiple Choice

Determine the distance acroos the river.

• 45 feet

• 50 feet

• 26 feet

• 54 feet