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WAEC Further Mathematics 2007 Question 3

Question 3

Trigonometry

Which of the following is the same as sin (270 + x)?

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

Answer: D (− cos x)

Explanation

sin(270° + x) = sin 270° cos x + cos 270° sin x = (−1)cos x + 0 = −cos x.