11.3 Perimeter and Area of Similar Figures
Two rectangles are similar. One has width 4 in. and length 6 in. The other has width of 6 in. and length of 9 in. What is the scale factor of the similar rectangles? What is the ratio of their perimeters? What is the ratio of their areas?
Example: A small flat screen TV is 24 in. wide and 18 in. long. A larger TV is similar to the smaller one. The area of the larger screen is 675 square inches. Find the width of the larger TV.
Example: The Pentagon in Washington, D.C., is a regular pentagon. Each side of the base is about 900 ft. and the area is about 1,400,000 square feet. You have a scale model of the Pentagon for which the perimeter of the base is 30 yd. Find the area of the base of the model to the nearest square foot.
Example: The ratio of the areas of two regular decagons is 20:36. What is the ratio of their corresponding side lengths in simplest radical form?
Homework: p.740, #3,4, 5-13odd, 16, 27