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WAEC Mathematics 2021 Question 19

Question 19

Mensuration of Plane Shapes

The height of an equilateral triangle is 10√3 cm. Calculate its perimeter.

  1. A.20 cm
  2. B.60 cm
  3. C.40 cm
  4. D.30 cm
Show the answer and explanation

Answer: B (60 cm)

Explanation

Height = side × sin 60° = side × √3/2, so side = 20 cm and the perimeter is 60 cm.