ECZ 2025 · GCE Paper 1 — Circle Theorems
Use the diagram. A, B, C, D and E lie on a circle with centre O, angle ADB = 18°, angle EAD = 31° and BC = CD. The chord AD crosses EO at X. Find angle EXD.
- A. 49°
- B. 80°
- C. 62°
- D. 100°
Verified working — step 1
The angle at the centre is twice the angle at the circumference: angle EOD = 2 × 31° = 62°. O lies on the diameter BD, so angle ODX = angle ADB = 18°. In triangle OXD, the exterior angle at X equals the sum of the two opposite interior angles: angle EXD = 62° + 18° = …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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