WAEC Mathematics 2022 Objective — Question 30

Question 30 of 50 from the West African Examinations Council (WAEC) Mathematics 2022 Objective paper, with the correct answer and a full explanation.

In the diagram, MNR is a tangent to the circle centre O at N and ∠NOS=108°. Find ∠OSN.

• A. 72°
• B. 42°
• C. 36°Correct
• D. 18°

Explanation

Triangle ONS is isosceles (ON=OS, radii). ∠ONS+∠OSN+108°=180°, and ∠ONS=∠OSN, so 2∠OSN=72°, giving ∠OSN=36°.

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