# Lesson 10 Homework Practice Indirect Measurement Shadow

**Use appropriate tools strategically.**

Mathematically proficient students start by explaining to themselves the meaning of a problem and looking for entry points to its solution. They analyze givens, constraints, relationships, and goals. They make conjectures about the form and meaning of the solution and plan a solution pathway rather than simply jumping into a solution attempt. They consider analogous problems, and try special cases and simpler forms of the original problem in order to gain insight into its solution. They monitor and evaluate their progress and change course if necessary. Older students might, depending on the context of the problem, transform algebraic expressions or change the viewing window on their graphing calculator to get the information they need. Mathematically proficient students can explain correspondences between equations, verbal descriptions, tables, and graphs or draw diagrams of important features and relationships, graph data, and search for regularity or trends. Younger students might rely on using concrete objects or pictures to help conceptualize and solve a problem. Mathematically proficient students check their answers to problems using a different method, and they continually ask themselves, "Does this make sense?" They can understand the approaches of others to solving complex problems and identify correspondences between different approaches.

## Presentation on theme: "Lesson 9-7 Pages 471-475 Similar Triangles and Indirect Measurement Lesson Check 9-6 Lesson Check 9-5."— Presentation transcript:

1 Lesson 9-7 Pages 471-475 Similar Triangles and Indirect Measurement Lesson Check 9-6 Lesson Check 9-5

2 What you will learn! 1.How to identify corresponding parts and find missing measures of similar triangles. 2.Solve problems involving indirect measurement using similar triangles.

3 Similar triangles Indirect measurement

4 What you really need to know! Similar triangles are triangles that have the same shape but not necessarily the same size. If two triangles are similar, then the corresponding angles have the same measure, and the corresponding sides are proportional.

5 What you really need to know! The properties of similar triangles can be used to find measurements which are difficult to measure directly. This is called indirect measurement.

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7 Example 1: If ∆RUN ~ ∆CAB, what is the value of x?

8 Example 2: A surveyor wants to find the distance RS across the lake. He constructs ∆PQT similar to ∆PRS and measures the distances as shown. What is the distance across the lake?

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10 Example 3: Suppose the John Hancock Center in Chicago, Illinois, casts a 257.5 foot shadow at the same time a nearby tourist casts a 1.5 foot shadow. If the tourist is 6 feet tall, how tall is the John Hancock Center?

11 x 257.5 ft 6 ft 1.5 ft

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13 Page 473 Guided Practice #’s 3-6

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15 Pages 471-473 with someone at home and study examples! Read:

16 Homework: Pages 474-475 #’s 7-18 #’s 21-22, 26, 27, 29-35 Lesson Check 9-7

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21 Page 747 Lesson 9-7

22 Lesson Check 9-7

23 Study Guide and Review Pages 483-485 #’s 1-24, 34-35 (Odd answers in back of book)

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33 Prepare for Test! Pages 487 #’s 1-14, 16, 20 Lesson Check Ch-9Lesson Check 9-7

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37 Prepare for Test! Pages 488-489 #’s 1-23

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