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Question
A bird is flying from A towards B at an angle of 35°, a point 30 km away from A. At B it changes its course of flight and heads towards C on a bearing of 48° and distance 32 km away. How far is B to the West of A?
(sin 55° = 0.8192, cos 55° = 0.5736, sin 42° = 0.6691, cos 42° = 0.7431)
Solution
Distance from B to the west of A is AB’
In ∆ABB’
cos 55° = `"AB’"/"AB"`
0.5736 = `"AB’"/30`
∴ AB’ = 0.5736 × 30
= 17.21 km
Distance of B to the West of A is 17.21 km
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