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JAMB Mathematics 1995 Question 38

Question 38

Differentiation

The derivative of cosec x is

  1. A.tan x cosec x
  2. B.−cot x cosec x
  3. C.tan x sec x
  4. D.−cot x sec x
Show the answer and explanation

Answer: B (−cot x cosec x)

Explanation

cosec x = (sin x)−1, so its derivative is −(sin x)−2 × cos x = −(cos x/sin x)(1/sin x) = −cot x cosec x.