McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
Study Guide and Review
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Exercise 16 Page 607

Begin by identifying the pairs of congruent angles, then compare the ratios ofcorresponding sides.

Are the Figures Similar? Yes.
Example Similarity Statemnt: PQRS ~ WXYZ
Scale Factor: 32

Practice makes perfect

To determine whether two polygons are similar, we need to follow two steps.

  1. Identify pairs of congruent angles.
  2. Compare the ratios of corresponding sides.
Let's analyze the given polygons.

Identifying Congruent Angles

Since all angles of a rectangle are right angles and all right angles are congruent, we know that the corresponding angles must be congruent. ∠ P ≅ ∠ W ∠ Q ≅ ∠ X ∠ R ≅ ∠ Y ∠ S ≅ ∠ Z

Comparing the Ratios

Now, let's compare the ratios of the corresponding sides. Recall that the included side between a pair of angles of one polygon corresponds to the included side between the corresponding pair of congruent angles of another polygon.

Corresponding Sides Ratio Substitute Lengths Simplify
P Q, W X PQ/WX 15/10 3/2
Q R, X Y QR/XY 9/6 3/2
R S, Y Z RS/YZ 15/10 3/2
S P, Z W SP/ZW 9/6 3/2

As we can see, all of the ratios are equal. Therefore, the given polygons are similar and the scale factor is 32. PQRS ~ WXYZ