ECZ 2021 · O-Level Paper 1 — Circle Theorems
The points A, B, C and D are on the circumference of a circle centre O, such that angle AOC = 126°. AO is parallel to DC and angle OCB = 33°. Find (b) OCD.
- A. 126°
- B. 72°
- C. 63°
- D. 54°
Verified working — step 1
AO is parallel to DC with OC as the transversal, so angle AOC and angle OCD are co-interior (allied) angles and add to 180°: angle OCD = 180° − 126° = …The full step-by-step working and final answer are included with Premium — checked against ECZ marking standards.
Original examination question © Examinations Council of Zambia. Worked solution and commentary © G12 Titan — not to be reproduced without permission.
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