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Do Now. DWP # 80. 3/20/ 2013 9-3 C Area of Composite Figures. To find the area of ANY composite figure, separate it into figures that you know how to solve for. Example 1. Find the area of the figure. Area of Rectangle Area of Triangle.

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Do Now

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  1. Do Now • DWP #80

  2. 3/20/2013 9-3 C Area of Composite Figures

  3. To find the area of ANY composite figure, separate it into figures that you know how to solve for

  4. Example 1 Find the area of the figure.

  5. Area of Rectangle Area of Triangle The height of the triangle is 14 – 10 or 4 centimeters. A = bh A = 10 ● 15 or 150 The area is 150 + 10 or 160 square centimeters.

  6. Example 2 The diagram shows the dimensions of a window. Find the area of the window. Round to the nearest tenth. The figure can be separated into a semicircle and a rectangle. The height of the rectangle is 7.2 – 1.7, or 5.5 feet.

  7. 2 or about The area of the rectangle is 3.4 × 5.5 or 18.7 square feet. The area of the window is 4.5 + 18.7 or about 23.2 square feet.

  8. Example 3 Find the area of the figure. The figure can be separated into two rectangles. The shared square, however, will be counted twice if the areas are added, so the area ofthe small square, 1 × 1, or 1 square meter, must be subtracted from the total. The area of the top rectangle is 5 × 2 or 10 square meters. The area of the bottom rectangle is 2 × 6 or 12 square meters. The sum of the areas is 10 + 12 or 22 square meters. So, the area of the figure is 21 square meters.

  9. 1.7 cm 1.3 cm 4.9 cm 2.1 cm Example 4 Find the area of the polygon.

  10. 1.7 cm 1.3 cm 4.9 cm 2.1 cm A =lw A =lw A = 4.9•1.7 A = 2.1 •1.3 A = 8.33 A = 2.73 8.33 + 2.73 = 11.06 The area of the polygon is 11.06 cm2.

  11. Example 5 Find the area of the polygon.

  12. 1 __ A =bh 2 1 __ A = •28 •12 2 A =lw A = 28•24 A = 168 A = 672 672 + 168 = 840 The area of the polygon is 840 ft2.

  13. Example 6 Patrick made a design. Use the coordinate grid to find its area. Rectangle 1 25 l = 5, w = 5; A = 5 • 5 = 25 20 Rectangle 2 15 l = 10, w = 5; A = 10 • 5 = 50 10 Rectangle 3 5 l = 15, w = 5; A = 15 • 5 = 75 0 10 5 15 20 25 Rectangle 4 l = 20, w = 5; A = 20 • 5 = 100

  14. 25 + 50 + 75 + 100 = 250 square units. The area of the design is 250 square units.

  15. Your Turn!

  16. 1. Find the area of the figure shown. 220 units2 2. Phillip designed a countertop. Use the coordinate grid to find its area. 30 units2

  17. 1. Find the area of the figure. A. 27 units2B. 54 units2 C. 93 units2D. 98 units2

  18. Homework • Pg. 563 #1-20 Evens • Study for Chapter 9 Quiz II

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