ECZ 2024 · O-Level Paper 2 · Question 12 — Trigonometry

Question from ECZ 2024 · O-Level Paper 2 · Question 12

(a) In triangle PQR, PQ = 16.1 m, angle QPR = 42° and angle PQR = 53°. Calculate the

Diagram for part (a)

(a(i)) length of QR,[4]

Verified working — step 1

The third angle: angle PRQ = 180 - 42 - 53 = 85°.

(a(ii)) area of triangle PQR,[2]

Verified working — step 1

Two sides and the included angle at Q: Area = (12)(PQ)(QR) sin(PQR)

(a(iii)) shortest distance from R to PQ.[2]

Verified working — step 1

The shortest distance is the perpendicular height h from R onto PQ.

(b) Solve the equation 6 sin θ = -3, for 180° ≤ θ ≤ 360°.[2]

Verified working — step 1

sin θ = -36 = -12, with related acute angle 30°.

(c) Simplify x3 - 9xx + 3.[2]

Verified working — step 1

Factor x out first: x3 - 9x = x(x2 - 9)

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Original examination question © Examinations Council of Zambia. Worked solution and commentary © G12 Titan — not to be reproduced without permission.

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