ECZ 2013 · O-Level Paper 1 — Circle Theorems

A circle centre O passes through the points A, B, C and D. Angle AOC = 110 degrees and AO is parallel to BC. Find angle ABC.

Diagram for ECZ 2013 · O-Level Paper 1
  • A. 55 degrees
  • B. 110 degrees
  • C. 125 degrees
  • D. 145 degrees

Verified working — step 1

B lies on the major arc, so angle ABC stands on the reflex angle AOC = 360 - 110 = 250 degrees. The angle at the circumference is half the angle at the centre: 2502= …

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Original examination question © Examinations Council of Zambia. Worked solution and commentary © G12 Titan — not to be reproduced without permission.

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