ECZ 2012 · O-Level Paper 1 — Circle Theorems
In the diagram, AT and TB are tangents to the circle at A and B, angle CAO = 30 degrees and angle CBO = 29 degrees. Calculate angle ATB.
- A. 118 degrees
- B. 59 degrees
- C. 121 degrees
- D. 62 degrees
Verified working — step 1
The angle at the centre is twice the angle at the circumference: angle AOB = 2 x 59 = 118 degrees. A tangent meets a radius at 90 degrees, so in quadrilateral OATB, angle ATB = 360 - 90 - 90 - 118 = …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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