What is the perimeter of the shaded region?

Consider the following for the next two (02) items that follow:<br>Let ABCD be the diameter of a circle of radius 6 cm. The lengths AB, BC and CD are equal. Semi-circles are drawn with AB and BD as diameters as shown in the figure given below.

  1. A. 24 cm
  2. B. 18\pi cm
  3. C. 15 cm
  4. D. 12\pi cm

Correct Answer: D. 12\pi cm

Explanation

The perimeter of the shaded region is the sum of the arc lengths of the three semi-circles. The arc length of a semi-circle is \pi r. Summing the three arcs: \pi(6) + \pi(4) + \pi(2) = 12\pi cm.

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