Using Similar Figures Chapter 5 Section 5.5

Objective The students will learn to use the proportions to find missing lengths in similar figures.

Vocabulary Polygon – a closed plane figure formed by three or more line segments that do not cross

Key Concept Two polygons are similar polygons if - corresponding angles have the same measures -the lengths of the corresponding sides form equivalent ratios 40° 40° 6 12 10 5 50° 4 90° 90° 50° 8

Example Write a proportion 𝐴𝐶 𝑂𝐷 = 𝐴𝑇 𝑂𝐺 Substitute 𝑥 50 = 24 30 D C 40 cm 32 cm 50 cm G x cm T 24 cm 30 cm A O Write a proportion 𝐴𝐶 𝑂𝐷 = 𝐴𝑇 𝑂𝐺 Substitute 𝑥 50 = 24 30 Simplify 𝑥 50 = 4 5 Solve x(5) = 50(4)  5x = 200 divide by 5 x= 40

Example Find the value of x. D A x cm 3 cm 16 cm G 4 cm C 2 cm 8 cm B E

Exit Ticket Find the value of x. D A 10 cm 4 cm 12.5 cm G x cm C B E

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