ECZ 2017 · O-Level Paper 1 — Circle Theorems
In the diagram below, A, B, C, D, E and F are points on the circumference of a circle. Angle FBD = 70° and angle AEF = 20°. Given that AD is a diameter, find angle DEF.
- A. 70°
- B. 90°
- C. 110°
- D. 160°
Verified working — step 1
AD being a diameter unlocks the semicircle right angle at E - then angle DEF is that right angle plus the given 20° slice.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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