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JAMB Mathematics 2006 Question 14

Question 14

Differentiation

Differentiate (cos θ − sin θ)2 with respect to θ.

  1. A.−2 cos 2θ
  2. B.−2 sin 2θ
  3. C.1 − 2 cos 2θ
  4. D.1 − 2 sin 2θ
Show the answer and explanation

Answer: A (−2 cos 2θ)

Explanation

(cos θ − sin θ)2 = 1 − 2 sin θ cos θ = 1 − sin 2θ, whose derivative is −2 cos 2θ.