Perimeter and area of composite shapes involving circles

Calculate the perimeter and area of composite shapes built from rectangles or squares combined with semicircles or quarter circles, leaving answers in terms of pi where appropriate and rounding appropriately otherwise.

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Te reo Māori terms

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Learning objective overview

Master Teaching Guide coverage for this objective.

Resources

Terminology

  • composite shape
  • quadrant
  • arc length

Task goals

  • Calculate the perimeter of a composite shape made from a rectangle or square with a semicircle attached to one side, using pi approximately equal to 3.14.
  • Calculate the area of a composite shape made from a rectangle or square with a semicircle attached to one side, using pi approximately equal to 3.14.
  • Calculate the remaining perimeter or area of a square or rectangle after a quarter circle has been cut from one corner, using pi approximately equal to 3.14.
  • Calculate the perimeter and area of a stadium or running-lane shape made from two straight sides and two semicircular ends, using pi approximately equal to 3.14.
  • Calculate a composite perimeter or area in exact form, leaving the answer in terms of pi, for the same rectangle-plus-circle and square-minus-quarter-circle shapes.
  • Find the area inside a square but outside an inscribed circle formed by four quarter circles drawn at its corners, or the total curved length of those quarter circles, in terms of pi.
  • Given the total perimeter or area of a composite circle-rectangle shape expressed in terms of pi, work backwards to find an unknown side length or radius.
  • Solve a composite-shape perimeter or area problem set in a real-world context, such as finding the cost of fencing around a composite shape, with the answer in terms of pi.

Teaching guidance

  • Students should be able to leave answers in terms of π and round appropriately.
  • It will benefit students if they go beyond semi and quarter circles (i.e. sectors).

Key skills

  • Perimeter
  • Area
  • Composite shapes
  • Circles
  • Semicircles
  • Quarter circles
  • Arc length

Quick stats

  • 81 total questions
  • 3 difficulty levels
  • Answers included