volume_mute

Find the area of the following composite shape

publish date2020/11/13 02:54:00 GMT+11

volume_mute

Unit of measurement is in cm2

complex-shape-7.jpg

123.285
300
176.715
130
125

Correct Answer

123.285

Explanation

  1. This shape represents a rectangle with length = 20 and width = 20.  There are half circles with bending inside this rectangle.  Each half circle has the same diameter = 15.  So, it is a rectangle area where the area of the circle is taken away from it.
  2. So the area of the shape could be written as 
    • Area = Arectangle - Acircle
  3. Write rectangle and circle area rules
    • Arectangle = lw
    • Acircle = πr2
  4. Calculate rectangle area where l = 20 cm and w = 15 cm
    • Arectangle = 15 * 20 = 300 cm2
  5. Calculate circle area where r = 7.5 cm   (half the diameter which is 15 cm)
    • Acircleπ * 7.52 = 176.715 cm2
  6. Calculate the required area
    • Area = 300 - 176.715 = 123.285 cm2

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