Big Ideas Math Geometry, 2014
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Big Ideas Math Geometry, 2014 View details
2. Congruent Polygons
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Exercise 12 Page 243

Show that corresponding parts are congruent.

See solution.

Practice makes perfect

We can show that two figures are congruent by showing that all their corresponding parts are congruent.

Corresponding angles

Let's analyze the given figures.

We can see that we are given markers on ∠ X and ∠ Z. They indicate that these angles are congruent. To find another congruent angles, we can use the fact that WY is a transversal of sides XY and WZ.

This means ∠ XYW and ∠ YWZ as well as ∠ XWY and ∠ WYZ are pairs of alternate interior angles.

Since XY∥ WZ, we know by the Alternate Interior Angles Theorem that these angle pairs are congruent. Therefore, all the corresponding angles are congruent.

Corresponding Sides

To determine the congruency of the corresponding sides, let's first find the corresponding pairs on the graph.

Now, we can compare them. Similarly as with the angles, we are given markers on sides. Note that WY corresponds to itself, so by the Reflexive Property of Congruence, WY ≅ YW.

Side Corresponding side Congruent
XW YZ Yes
XY WZ Yes
WY YW Yes

We found that all the pairs of corresponding sides are congruent. Since all the corresponding parts are congruent, the figures are congruent. To write an example congruent statement, we need to present corresponding vertices in the same order. W corresponds to Y X corresponds to Z Y corresponds to W Therefore, we can say that W XY ≅ Y ZW.