4MA1/2FR Jun 2019, Question 27: Choosing the Right Trigonometric Ratio
Pearson Edexcel International GCSE Mathematics A 4MA1 · Paper 2FR (Foundation) · Calculator · 5 marks
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The question, in short
Find side AB in a triangle split by a perpendicular from B to AC, using angles 42° and 32° and BC = 3.1 m, to 3 significant figures.
Summarised in our own words. Use the official paper for the exact wording and the diagram.
Solution · 5 marks
- 1In triangle BCD: sin 32° = BD ÷ 3.1
- 2BD = 3.1 × sin 32° = 1.6427...
- 3In triangle ABD: cos 42° = BD ÷ AB
- 4AB = 1.6427... ÷ cos 42°
- 5AB = 2.2105... = 2.21 m
Answer2.21
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