In the diagram, KS is a tangent to the circle centre O at R and ∠ROQ = 80o. Find ∠QRS.

  • A 90o
  • B 80o
  • C 50o
  • D 40o
waec 2004mathematics

The correct answer is D. 40o

QOP = 180 - 100(straight line angle) â†’ 80°

OPQ and OQP are isosceles of 40° each.

∠QRS = ∠RPQ (theorem: angle in the alternate segment are equal)

∠RPQ = 40o

∠QRS = 40o

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