ECZ 2017 · O-Level Paper 2 · Question 7 — Trigonometry

Question from ECZ 2017 · O-Level Paper 2 · Question 7

(a) The diagram below shows the location of houses for a village Headman (H), his Secretary (S) and a Trustee (T). H is 1.3 km from S, T is 1.9 km from H and angle THS = 130°. Calculate

Diagram for part (a)

(a(i)) the area of triangle THS,[2]

Verified working — step 1

Two sides TH and HS enclose the angle at H, so use the area rule.

(a(ii)) the distance TS,[5]

Verified working — step 1

Two sides and the included angle: cosine rule.

(a(iii)) the shortest distance from H to TS.[2]

Verified working — step 1

The shortest distance is the perpendicular height h from H to TS.

(b) Find the angle between 0° and 90° which satisfies the equation cos θ = 23.[1]

Verified working — step 1

cos θ = 23 = 0.6667.

(c) Simplify 2x2 - 8x + 2.[2]

Verified working — step 1

Factor the numerator: 2x2 - 8 = 2(x2 - 4) = 2(x - 2)(x + 2).

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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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