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JAMB Mathematics 1990 Question 22

Question 22

Triangles and Quadrilaterals

The lengths of the sides of a right-angled triangle are x cm, (3x − 1)cm and (3x + 1) cm. Find x.

  1. A.5
  2. B.7
  3. C.8
  4. D.12
Show the answer and explanation

Answer: D (12)

Explanation

The longest side is 3x + 1, so (3x + 1)2 = x2 + (3x − 1)2. This simplifies to 12x = x2, so x = 12.