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Consider the changes in the diagrams and the changes in the coordinates of the vertices of the triangles to transform â–ł DEF to â–ł PQR.
Example Answer: A reflection over the y-axis and then a dilation with a scale factor 13.
We will identify the similarity transformation that maps the blue preimage to the green image.
We will begin by reflecting the preimage over the y-axis. To do so, we will apply the Coordinate Rules for Reflections. Let's recall the rule, especially the one about reflection over the y-axis!
The Coordinate Rule for Reflection Over the y-Axis |
If (a,b) is reflected in the y- axis, then its image is the point (-a,b). |
With this information, we will reflect each vertex of â–ł DEF over the y-axis.
(a,b) → (-a,b)
D(-3,6) → D'(3,6)
E(-3,3) → E'(3,3)
F(-9,3) → F'(9,3)
Now, we will draw the image of reflection, â–ł D'E'F'.
Next, we will reduce △ D'E'F' with a scale factor of 13. To do so we will multiply the coordinates of each vertex by 13. This transformation is called dilation with a scale factor of 13. Note that by the Coordinate Rule for Dilation the center of dilation is at the origin, (0,0). (x,y) → (13x,13y) D'(3,6) → P(1,2) E'(3,3) → Q(1,1) F'(9,3) → R(3,1) Finally, we have transformed △ DEF to △ PQR.
Therefore, the similarity transformation is a reflection over the y-axis and then a dilation with a scale factor of 13. Take note that this is just one possible way of doing the similarity transformation, and your answer may vary.