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OAU Post-UTME Mathematics 2014 Question 18

Question 18

Trigonometry

If cos A = 12/13 and A is an acute angle, find (1 + tan2A)

  1. A.144/25
  2. B.25/144
  3. C.169/25
  4. D.169/144
Show the answer and explanation

Answer: D (169/144)

Explanation

1 + tan²A = sec²A = 1/cos²A = (13/12)² = 169/144.