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JAMB Mathematics 1993 Question 41

Question 41

Trigonometry

If two angles of a triangle are 30° each and the longest side is 10cm, calculate the length of each of the other sides.

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

Answer: D (10√3/3 cm)

Explanation

The third angle is 120°, opposite the 10cm side. By the sine rule, each other side = 10 sin 30°/sin 120° = 5 ÷ (√3/2) = 10/√3 = 10√3/3 cm.