0580/21 Oct/Nov 2021, Question 9: The Cosine Ratio
Cambridge IGCSE Mathematics 0580 · Paper 21 (Extended) · Calculator · 2 marks
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The question, in short
Use the right-angled triangle with base 7 cm and hypotenuse 12 cm to calculate the angle x° at the bottom right.
Summarised in our own words. Use the official paper for the exact wording and the diagram.
Solution · 2 marks
- 17 cm is adjacent to x and 12 cm is the hypotenuse
- 2cos x = 7/12
- 3x = cos⁻¹(7/12) = 54.31… ≈ 54.3
Answer54.3 or 54.31…
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