ECZ 2010 · O-Level Paper 1 — Circle Theorems
In the diagram, O is the centre of circle ABCD and ECT is a tangent at C. Explain why angle OCT = 90°.
- A. Because a tangent is perpendicular to the radius at the point of contact
- B. Because angle OCT is an angle in a semicircle
- C. Because OC and CT are equal in length
- D. Because OCT is an exterior angle of the circle
Verified working — step 1
OC is a radius drawn to the point of contact C, and ECT is the tangent there. A tangent meets a radius at right angles, so angle OCT = …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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