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JAMB Mathematics 1991 Question 33

Question 33

Triangles and Quadrilaterals

One angle of a rhombus is 60°. The shorter of the two diagonals is 8cm long. Find the length of the longer one.

  1. A.8√3
  2. B.16/√3
  3. C.5√3
  4. D.10/√3
Show the answer and explanation

Answer: A (8√3)

Explanation

The shorter diagonal cuts the rhombus into two equilateral triangles, so each side is 8cm. The longer diagonal is twice the height of such a triangle: 2 × 4√3 = 8√3cm.