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UI Post-UTME Mathematics 2023 (Model questions) Question 3

Question 3

Trigonometry

If sin x = 3/5 and x is in the second quadrant, what is cos x?

  1. A.−4/5
  2. B.−3/5
  3. C.3/4
  4. D.4/5
Show the answer and explanation

Answer: A (−4/5)

Explanation

The adjacent side is √(5² − 3²) = 4, so |cos x| = 4/5; cosine is negative in the second quadrant, giving −4/5.