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WAEC Further Mathematics 2011 Question 4

Question 4

Trigonometry

Evaluate cos(π/2 + π/3)

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

Answer: B (−√3/2)

Explanation

cos(π/2 + π/3) = cos(π/2)cos(π/3) − sin(π/2)sin(π/3) = 0 − √3/2 = −√3/2.