ECZ 2021 · GCE Paper 2 · Question 7 — Trigonometry
In triangle ABC, AB = 275m, AC = 45m and BC = 300m.
(a(i)) Calculate angle BAC.[5]
Verified working — step 1
Use the Cosine Rule with A between sides AB and AC:(a(ii)) Calculate the area of triangle ABC.[2]
Verified working — step 1
Area = 12× AB × AC × sin A(a(iii)) Calculate the shortest distance from A to BC.[2]
Verified working — step 1
Let h be the shortest distance from A to BC.(b) Solve the equation cos θ = -0.5 for 180° ≤ θ ≤ 360°.[1]
Verified working — step 1
cos θ = -0.5(c) Simplify (18a2 b16c3 d2) ÷ (24a15cb3) × (8c2 d3 / 30a3 b).[2]
Verified working — step 1
Rewrite division as multiplication by the reciprocal: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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