Lesson 24 Ratios Rates and Percents Ratios and
- Slides: 9
Lesson 24 Ratios, Rates and Percents Ratios and Similar Figures
Warm-Up 1. Sketch two congruent rectangles. 2. Sketch two similar, but not congruent, triangles. 3. Find the perimeter of the shape below.
Ratios and Similar Figures Target: Find missing sides or perimeters of figures using ratios.
Example 1 Two similar figures are shown below. Find the ratio of the smaller figure’s perimeter to the larger figure’s perimeter. � Find � The ratio of sides. ratio of the perimeters is or 1: 2.
Example 2 Given the similar figures, use ratios to find the missing perimeter. � Find ratio of corresponding sides. � Find ratio of perimeters. � Ratio of perimeters equals ratio of corresponding sides. Use equivalent fractions to find the larger perimeter. � The perimeter of the triangle is 36 inches.
Example 3 Given the similar figures and perimeters, use ratios to find the length of the missing side. � Find ratio of perimeters. � Find ratio of corresponding sides. � Ratio of perimeters equals ratios of corresponding sides. Use equivalent fractions to find the missing side. � The missing side is 10 feet.
Exit Problems 1. Find the ratio of the perimeters in the pair of similar figures given. 2. The circumferences for a pair of similar circles are shown. Find the ratio of the corresponding diameters. 3. The ratio of corresponding sides of two similar triangles is : 3. The larger triangle has a perimeter of 12 cm. Find the perimeter of the smaller triangle. 2
Communication Prompt When two shapes are similar, why is the ratio of their corresponding sides equal to the ratio of their perimeters? Use an example to help you explain.