1 / 19

Warm Up

Preview. Warm Up. California Standards. Lesson Presentation. Warm Up Find the area of each figure. Round to the nearest tenth, if necessary. 1. a trapezoid with bases 10 cm and 12 cm and height 5 m 2. a parallelogram with base 9 in. and height 8 in. 3. a semicircle with radius 5 m

lowri
Télécharger la présentation

Warm Up

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Preview Warm Up California Standards Lesson Presentation

  2. Warm Up Find the area of each figure. Round to the nearest tenth, if necessary. 1.a trapezoid with bases 10 cm and 12 cm and height 5 m 2. a parallelogram with base 9 in. and height 8 in. 3. a semicircle with radius 5 m 4. a semicircle with diameter 8 cm 55 cm2 72 in2 39.3 m2 25.1 cm2

  3. California Standards MG2.2 Estimate andcompute the area of more complex or irregular two-andthree-dimensional figures by breaking the figures down into more basic geometric objects.

  4. One method of estimating the area of an irregular figure is to count the number of squares the figure covers.

  5. The area of the figure is 12 square units. Additional Example 1: Finding Area by Counting Find the area of each figure. A. Count the full squares: 10 Count the half-full squares: 4 Add the number of full squares plus half the number of half-full squares: 10 + ( • 4) = 10 + 2 =12 1 2

  6. Helpful Hint For shapes such as the one in Example 1B you can only estimate the area.

  7. The area of the figure is approximately 13 square units. Additional Example 1: Finding Area by Counting Find the area of each figure. B. Count the full and almost-full squares: 11 Count the half-full squares: 4 Add the number of full squares plus half the number of half-full squares: 11 + ( • 4) = 11 + 2 =13 1 2

  8. The area of the figure is 15 square units. Check It Out! Example 1 Find the area of each figure. A. Count the full squares: 11 Count the half-full squares: 8 Add the number of full squares plus half the number of half-full squares: 11 + ( • 8) = 11 + 4 = 15 1 2

  9. The area of the figure is about 14 square units. Check It Out! Example 1 Find the area of each figure. B. Count the full and almost-full squares: 11 Count the half-full squares: 6 Add the number of full squares plus half the number of half-full squares: 11 + ( • 6) = 11 + 3 =14 1 2

  10. Additional Example 2A: Estimating Area Using Composite Figures Use a composite figure to estimate the shaded area. Draw a composite figure that approximates the irregular shape. Divide the composite figure into simple shapes.

  11. 1 1 __ __ 2 2 1 2 1 2 area of the trapezoid: area of the triangle: A = bh = (4•2) = 4 The shaded area is approximately 7 square units. A = h(b1+ b2) = 1(4 +2)= 3 Additional Example 2A Continued Use a composite figure to estimate the shaded area.

  12. Additional Example 2B: Estimating Area Using Composite Figures Use a composite figure to estimate the shaded area. Draw a composite figure that approximates the irregular shape. Divide the composite figure into simple shapes.

  13. 1 1 __ __ 2 2 A =bh = 1 •4 = 4 area of the rectangle: area of the semicircle: A = pr2 •3.14(22)  6.28 The shaded area is approximately 10.3 square units. Additional Example 2B Continued Use a composite figure to estimate the shaded area.

  14. Check It Out! Example 2A Use a composite figure to estimate the shaded area. Draw a composite figure that approximates the irregular shape. Divide the composite figure into simple shapes.

  15. 1 1 __ __ 2 2 A =bh = 3 •2 = 6 area of the rectangle: area of the triangle: A = bh = (3•2) = 3 The shaded area is approximately 9 square units. Check It Out! Example 2A Continued Use a composite figure to estimate the shaded area.

  16. Check It Out! Example 2B Use a composite figure to estimate the shaded area. Draw a composite figure that approximates the irregular shape. Divide the composite figure into simple shapes.

  17. 1 1 __ __ 2 2 A =s2 = 2 •2= 4 area of the square: area of the semicircle: A = pr2 •3.14(12)  1.57 The shaded area is approximately 5.5 square units. Check It Out! Example 2B Continued Use a composite figure to estimate the shaded area.

  18. 8 square units approximately 12 square units Lesson Quiz: Part l Find the area of each figure. 1. 2.

  19. approximately 4 square units approximately 6 square units Lesson Quiz: Part ll Use a composite figure to estimate the shaded area. 3. 4. 1 2

More Related