ECZ 2021 · GCE Paper 2 · Question 7 — Trigonometry
Question from ECZ 2021 · GCE Paper 2 · Question 7
(a) In triangle ABC below, AB = 275 m, AC = 45 m and BC = 300 m. Calculate
(a(i)) angle BAC,[5]
Verified working — step 1
All three sides known, so cosine rule for the angle at A:(a(ii)) the area of triangle ABC,[2]
Verified working — step 1
Two sides and the included angle at A: Area = (12)(AB)(AC) sin A(a(iii)) the shortest distance from A to BC.[2]
Verified working — step 1
The shortest distance is the perpendicular height h from A onto BC.(b) Solve the equation cos θ = -0.5 for which 180° ≤ θ ≤ 360°.[1]
Verified working — step 1
cos θ = -0.5, related acute angle 60°.(c) Simplify 18a2 b16c3 d2 ÷ 24a15cb3 × 8c2 d330a3 b.[2]
Verified working — step 1
Turn each division into multiplication by the reciprocal and combine step by step.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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