ECZ 2012 · O-Level Paper 1 — Trigonometry
In the diagram, BCD is a straight line, AB = 6 cm, BD = 13 cm, angle ACD = 135 degrees and angle ABC = 90 degrees. Calculate the length of CD.
- A. 7 cm
- B. 6 cm
- C. 13 cm
- D. 19 cm
Verified working — step 1
Angles on the straight line give angle ACB = 180 - 135 = 45 degrees. Triangle ABC is right-angled at B with a 45 degree angle, so it is isosceles and BC = AB = 6 cm. Then CD = BD - BC = 13 - 6 = …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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