ECZ 2025 · GCE Paper 1 — Circle Theorems
In the following diagram A, B, C, D and E are points on the circumference of a circle centre O. Angle ADB = 18°, angle EAD = 31° and BC = CD. Find angle ADC.
- A. 45°
- B. 18°
- C. 49°
- D. 63°
Verified working — step 1
Spot the diameter first: B, O and D are in line, so BD passes through the centre - and a diameter unlocks the right angle in a semicircle.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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