Glencoe Math: Course 3, Volume 2
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Glencoe Math: Course 3, Volume 2 View details
5. Similar Triangles and Indirect Measurement
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Exercise 5 Page 557

If two triangles are similar, then their corresponding angles are congruent and the lengths of their corresponding sides are proportional.

37.5 meters

Practice makes perfect

We are given a diagram and we want to find the distance from the log ride to the pirate ship. Let's first label and show that triangles are similar. Once we know that the triangles are similar, we can use their proportional relationship to find the missing distance.

From the angle markers shown in the diagram, we can see that all the corresponding angles are congruent. ∠ A ≅ ∠ D ∠ B ≅ ∠ C ∠ E ≅ ∠ E

Since at least two of the three angles of △ ABE are congruent to two angles of △ DCE, they are similar by the rule for Angle-Angle (AA) Similarity. △ ABE ~ △ DCE Now, notice that AE corresponds to DE and BE corresponds to CE.

Remember that corresponding sides of similar figures will have proportional lengths. We know that AE= 25 meters, DE= 8 meters, and CE= 12 meters. We can use these lengths to write a proportion. AE/DE=BE/CE ⇔ 25/8=BE/12 Let's solve this proportion using cross products.
25/8=BE/12
25 * 12 = 8 * BE
Solve for BE
300 = 8 * BE
300/8 = 8 * BE/8
37.5 = 8 * BE/8
37.5 = 8/8 * BE
37.5 = 1 * BE
37.5 = BE
BE = 37.5
The distance from the log ride to the pirate ship is 37.5 meters.