ECZ 2015 · O-Level Paper 1 — Circle Theorems
In the diagram, A, B, C and D are points on the circumference of a circle with centre O. ADE and BCE are straight lines, angle CED = 28° and angle BCA = 43°. Find angle CDE.
- A. 62°
- B. 28°
- C. 90°
- D. 47°
Verified working — step 1
BD passes through the centre O, so angle DCB = 90° (angle in a semicircle). Angles on the straight line BCE give angle DCE = 180° − 90° = 90°. In triangle CDE: angle CDE = 180° − 90° − 28° = …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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