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WAEC Mathematics 1994 Question 44

Question 44

Trigonometry

Cos 57° has the same value as

  1. A.sin 213°
  2. B.− cos 303°
  3. C.sin 147°
  4. D.cos 123°
  5. E.cos 237°
Show the answer and explanation

Answer: C (sin 147°)

Explanation

cos 57° = sin 33°, and sin 147° = sin(180° − 33°) = sin 33°. The other options are all negative.