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WAEC Mathematics 2005 Question 20

Question 20

Mensuration of Plane Shapes

What is the diameter of a circle of area 77cm2? (Take π = 22/7)

  1. A.√2/7 cm
  2. B.3 1/2 cm
  3. C.7cm
  4. D.7√2 cm
Show the answer and explanation

Answer: D (7√2 cm)

Explanation

r2 = 77 × 7/22 = 49/2, so r = 7/√2 and the diameter = 14/√2 = 7√2 cm.