ECZ 2019 · O-Level Paper 1 — Circle Theorems
In the diagram below, A, B, C and D are points on the circumference of a circle, centre O. DÂT = 40°, BDC = 30° and AT is a tangent to the circle at A. Calculate (c) AOB.
- A. 120°
- B. 50°
- C. 100°
- D. 80°
Verified working — step 1
From the tangent-chord theorem, ∠ABD = 40°.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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