7.7 The student, given appropriate dimensions, will estimate the area of polygons by subdividing them into rectangles and right triangles.

Directions 1

  • 1. What are the two geometric shapes used to create this figure?
  • 2. Move points A, E, D, and slider a separately. Describe what each of them does.
  • 3. Move point A to an intersection point on the grid.
    Estimate the area of the entire figure by counting the squares.
  • 4. Find the combined area of the two shapes.

Directions 2

  • 5. Find the area of each of the geometric shapes separately using their respective formula.
  • 6. Find the combined area of the two shapes.
  • Is your answer in step 6 reasonable when compared to the estimated area found in #4?
    Explain.
  • More irregular shapes

Hands-On Activities

  • More irregular shapes
  • Shodor Choose the perimeter of the shape and the computer will generate the shape on a grid. You are to identify the area.

Other Web Sites

  • Regentsprep Find the perimeter of polygons and circumference of circles.
  • Mathleague You will see examples on how to find the area of different shapes.
  • ExploreLearning Teachers have to assign the Maximize Area to their classes.

Lesson 3-1: Estimating the Area of Figures


See the directions on the right

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Created with GeoGebra by Rachel Valcin, Spring 2007.