Collect any late or redone homework (in your HW notebook) Dec. 6, 2012 Title: Activity Lab 5-5a (p. 251) Exploring Similar Figures Pre-Activity Questions: What makes two shapes similar? Are all triangles similar?

Activity Lab 5-5a on page 251 You’ll need your protractor and a pencil. How will you be graded on this? - on-task - helping others (bonus!) - neatly done - accurately done - How clearly did you answer question 4?

Two polygons are similar if Corresponding angles are equal; AND Using Similar Figures LESSON 5-5 Concept summary Two polygons are similar if Corresponding angles are equal; AND Lengths of corresponding sides form equivalent ratios 5-5

ABC is similar to DEF. Find the value of c. Using Similar Figures LESSON 5-5 Additional Examples ABC is similar to DEF. Find the value of c. = c 18 6 9 Write a proportion. Write the cross products. 9c = 18 • 6 Divide each side by 9. 9c 9 108 = Solve for c. c = 12 Quick Check 5-5

Write the cross products. 12x = 5 • 42 Using Similar Figures LESSON 5-5 Additional Examples A 5-ft person near a tree has a shadow 12 ft long. The tree has a shadow 42 ft long. What is the height of the tree? Draw a diagram like the one at the right. Let x represent the height of the tree. = x 5 42 12 Write a proportion. Write the cross products. 12x = 5 • 42 Divide each side by 12. 12x 12 5 • 42 = Simplify. x = 17 1 2 The height of the tree is 17 ft. 1 2 Quick Check 5-5

Using Similar Figures LESSON 5-5 Closure Q1) Angle measures of a triangle are 40, 60 and 80 degrees. Angle measures of a similar triangle will be? Q2) Side lengths of a triangle are 40 cm, 60 cm and 80 cm. Smallest length of a similar triangle is 120 cm. What are the lengths of the other two sides? 5-5

The angle measures would also be 40, 60, and 80 degrees. Using Similar Figures LESSON 5-5 Closure Q1) Angle measures of a triangle are 40, 60 and 80 degrees. Angle measures of a similar triangle will be? The angle measures would also be 40, 60, and 80 degrees. Q2) Side lengths of a triangle are 40 cm, 60 cm and 80 cm. Smallest length of a similar triangle is 120 cm. What are the lengths of the other two sides? The lengths of the other two sides are 180 cm and 240 cm. 5-5

In the figure below, JKL ~ XYZ. Using Similar Figures LESSON 5-5 Lesson Quiz – Write this in your Notes notebook In the figure below, JKL ~ XYZ. 1. Which angle besides K has measure 29°? 2. Find YZ. 3. A 4-ft-tall person standing near a telephone pole has a shadow 3 ft long. At the same time, the telephone pole has a shadow 18 ft long. What is the height of the telephone pole? Y 9 24 ft 5-5

Wednesday: Similar Figures and Indirect Measurement (handout) HOMEWORK Wednesday: Similar Figures and Indirect Measurement (handout) Thurs: Scale Model Project due (with rubric and calculations) 5-5