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JAMB Mathematics 1987 Question 38

Question 38

Trigonometry

The sine, cosine and tangent of 210° are respectively

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

Answer: A (−1/2, −√3/2, √3/3)

Explanation

210° is in the third quadrant with reference angle 30°, where sine and cosine are negative and tangent positive. So sin 210° = −1/2, cos 210° = −√3/2 and tan 210° = 1/√3 = √3/3.