 # 10-4 Perimeters and Areas of Similar Figures

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10-4 Perimeters and Areas of Similar Figures

Perimeters and Areas of Similar Figures
If the scale factor of two similar figures is 𝑎 𝑏 , then The ratio of their perimeters is 𝑎 𝑏 The ratio of their areas is 𝑎 2 𝑏 2

Problem 1: Finding Ratios in Similar Figures
The trapezoids are similar. The ratio of the lengths of corresponding sides is 𝑜𝑟 What is the ratio (smaller to larger) of the perimeters What is the ratio (smaller to larger) of the areas?

Two similar polygons have corresponding sides in the ratio 5:7
What is the ratio (larger to smaller) of their perimeters? What is the ratio (larger to smaller) of their areas?

Problem 2: Finding Areas Using Similar Figures
The are of the smaller regular pentagon is about 27.5 square cm. What is the best approximation for the area of the larger pentagon?

Problem 4: Finding Perimeter Ratios
The triangles are similar. What is the scale factor? What is the ratio of their perimeters?