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WAEC Mathematics 2011 Question 3

Question 3

Trigonometry

Given that cos x° = 1/r, express tan x° in terms of r.

  1. A.1/√r
  2. B.√r
  3. C.√(r2 + 1)
  4. D.√(r2 − 1)
Show the answer and explanation

Answer: D (√(r2 − 1))

Explanation

Draw a right triangle with adjacent side 1 and hypotenuse r. The opposite side is √(r2 − 1), so tan x° = √(r2 − 1)/1.