4MA1/2HR Jan 2021, Question 11: Arc Length
Pearson Edexcel International GCSE Mathematics A 4MA1 · Paper 2HR (Higher) · Calculator · 4 marks
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The question, in short
Find the perimeter of a shaded sector of a circle with centre O and radius 9 cm, using the 40° unshaded angle shown, to 3 significant figures.
Summarised in our own words. Use the official paper for the exact wording and the diagram.
Solution · 4 marks
- 1Sector angle = 360 − 40 = 320°
- 2Arc length = 320/360 × 2 × π × 9 = 16π = 50.26… cm
- 3Perimeter = arc + two radii = 50.26… + 9 + 9 = 68.26…
- 4To 3 significant figures: 68.3
Answer68.3
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