McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
6. Similarity Transformations
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Exercise 5 Page 596

Notice that △ JRS and △ JKL share ∠ J.

Example Solution: See solution.

Practice makes perfect

Let's use the given graph to read the coordinates of the original figure and the image of its dilation.

We can see that △ JRS and △ JKL share ∠ J, and we know that ∠ J ≅ ∠ J. Let's use the coordinates of the vertices to find the lengths of the sides of each triangle that include ∠ J.
Side Vertices Distance Formula Simplified
JK ( 0,0), ( - 6,2) sqrt(( - 6- 0)^2+( 2- 0)^2) 2 * sqrt(10)
JR ( 0,0), (- 3,1) sqrt((- 3- 0)^2+(1- 0)^2) sqrt(10)
JL ( 0,0), ( - 2,6) sqrt(( - 2- 0)^2+( 6- 0)^2) 2 * sqrt(10)
JS ( 0,0), ( - 1,3) sqrt(( - 1- 0)^2+( 3- 0)^2) sqrt(10)

Now, we can find the ratios between the corresponding sides. JR/JK=sqrt(10)/2 * sqrt(10) = 1/2 [1.2em] JS/JL=sqrt(10)/2 * sqrt(10) = 1/2 We can tell that these ratios are equivalent. Therefore, the lengths of two sides of △ JRS are proportional to the lengths of two corresponding sides of △ JKL, and the included angles are congruent. By the Side-Angle-Side Similarity Theorem, we can conclude that △ JRS is similar to △ JKL. △ JRS ~ △ JKL Therefore, the dilation is a similarity transformation.