Big Ideas Math Geometry, 2014
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Big Ideas Math Geometry, 2014 View details
6. Similarity and Transformations
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Exercise 5 Page 219

When a point is rotated 90^(∘) counterclockwise about the origin, the coordinates of the point will change such that (a,b)→ (- b,a).

Practice makes perfect

Before we apply the similarity transformations, let's graph the original △ FGH.

Rotation

To perform the rotation, we can use the coordinate rule. When a figure is rotated 90^(∘) counterclockwise about the origin, the coordinates of the figure's vertices change such that (a,b)→ (- b,a).

ccc (a,b) & → & (- b,a) [0.5em] F(- 2,2) & → & F'(- 2,- 2) G(-2,-4) & → & G'(4,-2) H(-4,-4) & → & H'(4,-4) Now we are able to graph △ F'G'H'.

Dilation

Next, we will dilate △ F'G'H' using a scale factor of 3. To do this, we need to multiply the coordinates by 3. ccccc (x,y) &→& (3x,3y) &→& (x',y') [0.8em] F'(-2,-2) &→& (3(-2),3(-2)) &→& F''(-6,-6) [0.8em] G'(4,-2) &→& (3(4),3(-2)) &→& G''(12,-6) [0.8em] H'(4,-4) &→& (3(4),3(-4)) &→& H''(12,-12) Now, we can show the dilation by plotting the newly obtained points.

Combined Transformation

Finally, we can remove the middle step and only look at the preimage and the image.