ECZ 2020 · O-Level Paper 1 — Trigonometry
The diagram shows triangle ABC in which angle ABC = 90°. BC is produced to D. Given that tan(angle BAC) = 43, find the value of cos(angle ACD).
- A. -45
- B. 45
- C. -35
- D. 35
Verified working — step 1
With the right angle at B and tan(angle BAC) = 43, the sides are BC = 4, AB = 3, AC = 5. Then cos(angle ACB) = BCAC= 45. Since D is on BC produced, angle ACD = 180° - angle ACB, so cos(angle ACD) = …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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