ECZ 2019 · GCE Paper 1 — Circle Theorems
In the diagram, A, B, C, D and E are points on the circumference of a circle with centre O. DE = AD, AĈB = 20° and AÔE = 80°. Find DÂE.
- A. 40°
- B. 55°
- C. 70°
- D. 35°
Verified working — step 1
In triangle ADE, the chords DE and AD are equal, so the triangle is isosceles with the angles at A and E equal. The angle at D is AD̂E = 40°, so the other two angles share 180° − 40° = 140° equally: DÂE = …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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