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Lesson Menu. Main Idea and New Vocabulary Key Concept: Similar Polygons Example 1: Identify Similar Polygons Example 2: Find Missing Measures Key Concept: Ratios of Similar Figures Example 3: Find Perimeter. Identify similar polygons and find missing measures of similar polygons.
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Lesson Menu Main Idea and New Vocabulary Key Concept: Similar Polygons Example 1: Identify Similar Polygons Example 2: Find Missing Measures Key Concept: Ratios of Similar Figures Example 3: Find Perimeter
Identify similar polygons and find missing measures of similar polygons. • similar polygons • corresponding parts • scale factor Main Idea/Vocabulary
Identify Similar Polygons Determine whether triangle DEF is similar to triangle HJK. Explain. First, check to see if corresponding angles are congruent. DH, EJ, and FK, so all corresponding angles are congruent. Example 1
Since , the corresponding sides are proportional. Identify Similar Polygons Next, check to see if corresponding sides are proportional. Answer: Therefore, the triangles are similar. Example 1
Determine whether the figures are similar. Explain. A.Yes; corresponding angles are congruent and corresponding sides are proportional. B.Yes; corresponding angles are congruent and corresponding sides are congruent. C.No; corresponding angles are congruent, but corresponding sides are not proportional. D.No; corresponding angles are congruent, but corresponding sides are not congruent. Example 1 CYP
scale factor: Find Missing Measures GEOMETRY Given that rectangle LMNO ~ rectangle GHIJ, find the missing measure. Find the scale factor from rectangle LMNO to rectangle GHIJ. Example 2
Write the equation. So, a length on rectangle LMNO is times as long as the corresponding length on rectangle GHIJ. Let m represent the measure ofON. Find Missing Measures m = 6 Multiply. Answer: m = 6 Example 2
GEOMETRY Given that quadrilateral KLMN ~ quadrilateral RSTU, find the missing measure. A. 6 B. 8 C. 10 D. 12 Example 2 CYP
Step 1The actual length is proportional to the length of the model with a ratio of . Find the scale factor. Find Perimeter BILLBOARDS A model of a billboard has a side length of 3 inches. The corresponding side on the actual billboard is 4 feet long. The model has a perimeter of 42 inches. What is the perimeter of the actual billboard? • Convert feet to inches and divide out units. Example 3
Find Perimeter Step 2 Find the perimeter of the actual billboard. P = 42 • 16 or 672 Substitute. Then simplify. perimeter of billboard = perimeter of model • scale factor Answer: The perimeter of the actual billboard is 672 inches or 56 feet. Example 3
PHOTOGRAPHS Aphotograph has a side length of 8 inches. The photo is enlarged to poster size and the corresponding side on the poster is 2 feet long. The photograph has a perimeter of 36 inches. What is the perimeter of the poster? A. 4 feet B. 4.5 feet C. 9 feet D. 18 feet Example 3 CYP