Shape and Space 7
2 marks · EasyA circle has a radius of 5 cm. The angle at the centre of a sector is 90°.
Calculate the length of the arc. Give your answer to 2 decimal places.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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7.85 cm (±0.02)
Also accept: 7.85
Common mistakes: Uses sector area formula.; Uses degrees instead of fraction in arc length.
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Marking points
M1 · 1 mark · Uses arc length formula: , with and .
A1 · 1 mark · Calculates value as 7.85 cm (accept rounding to 2 d.p.). (follow-through)
Worked solution
Arc length =
=
= 7.85 cm (2 d.p., using )