In the diagram, NR is a diameter, ∠MNR = x° and, ∠SRN = (5x +...

MATHEMATICS
WAEC 2023

In the diagram, NR is a diameter, ∠MNR = x° and, ∠SRN = (5x + 20)°. Find the value of 2x.

  • A. \(42^0\)
  • B. \(35^0\)
  • C. \(20^0\)
  • D. \(90^0\)

Correct Answer: B. \(35^0\)

Explanation

∠RMN = 90° (angles in a semicircle is a right angle)

∠SRN = ∠RMN + ∠MNR (ext. angle of a ? is equal to the sum of two opp. int. angles)

⇒ 5x + 20 = 90 + x

⇒ 5x - x = 90 - 20

⇒ 4x = 70

x = \(\frac{70}{4}\)

= 17.4°

therefore, 2x = 2\(\times17.5\) = 35°



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