Advanced Geometry Similarity Lesson 1 B Dilations Example

Advanced Geometry Similarity Lesson 1 B Dilations

Example: Find the measure of the dilation image or the pre-image of using the given scale factor. CD = 15, r = 3 C'D' = 7, r =

Example: Trapezoid EFGH has vertices E(-8, 4), F(-4, 8), G(8, 4), and H(-4, -8). Find the image of trapezoid EFGH after a dilation centered at the origin with a scale factor of. Graph the pre-image and the image.

To determine the scale factor of a dilation: • look at the coordinates of a point from the pre-image and the corresponding point from the image • divide the image coordinate by the pre-image coordinate Ex: D(8, -3) and D’(6, -2. 25) image = pre-image =

Example: Determine the scale factor used for each dilation with center C. Determine whether the dilation is an enlargement, reduction, or congruence transformation.

Example: Jamie is using a photo editing program to reduce posters that are 1 foot by 1. 5 feet to 9 inch by 13. 5 inch. What scale factor did he use?

Example: A 5 -inch by 7 -inch photograph has been enlarged by a factor of 150%. What are the new dimensions of the photograph? How has the area of the preimage changed?

Example: Find the perimeter of ΔABC. Graph the image of ΔABC after a dilation centered at the origin with scale factor -2. Find the perimeter of ΔA’B’C’ and compare it to the perimeter of ΔABC.