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JAMB Mathematics 2000 Question 23

Question 23

Trigonometry

Find the minimum value of the function f(θ) = 2/(3 − cosθ) for 0 ≤ θ ≤ 2π

  1. A.½
  2. B.⅔
  3. C.1
  4. D.2
Show the answer and explanation

Answer: A (½)

Explanation

cosθ lies between −1 and 1, so 3 − cosθ lies between 2 and 4. The fraction 2/(3 − cosθ) is smallest when the denominator is 4, giving 2/4 = ½.