When a 6-ft student casts a 17-ft shadow, a flagpole casts a shadow that is 51 ft long. Find the height of the flagpole. Similarity and Indirect Measurement COURSE 3 LESSON 5-8 Set up a proportion for the similar triangles. 17h = 6 51 Write the cross products. h = 18 Simplify. Divide each side by h = The height of the flagpole is 18 ft. Words Let h = the flagpole’s height. Proportion flagpole’s height student’s height length of flagpole’s shadow length of student’s shadow = h6h = 5-8

In the figure below, ABC ~ EDC. Find d. Similarity and Indirect Measurement COURSE 3 LESSON 5-8 = Use similar triangles to set up a proportion involving the lengths of corresponding sides. ED AB CD CB ED corresponds to AB. CD corresponds to CB. = d Substitute. 312 d = Write the cross products. 5-8

(continued) Similarity and Indirect Measurement COURSE 3 LESSON 5-8 The length of d is 188 m. 312d = 58,656 Simplify. 312d 58, = 58, Divide each side by 312. Use a calculator. 5-8

1.A 5-ft tall student casts a 12-ft shadow. A tree casts a 27-ft shadow. How tall is the tree? 2.A 6-ft man casts a 9-ft shadow. A sculpture casts a 45-ft shadow. How tall is the sculpture? Similarity and Indirect Measurement COURSE 3 LESSON ft tall 30 ft 5-8