A circle, with centre O and radius 6 cm, contains another circle, with centre O and radius x cm - OCR - GCSE Maths - Question 21 - 2018 - Paper 2
Question 21
A circle, with centre O and radius 6 cm, contains another circle, with centre O and radius x cm.
Write down an expression, in terms of π and x, for the shaded area ... show full transcript
Worked Solution & Example Answer:A circle, with centre O and radius 6 cm, contains another circle, with centre O and radius x cm - OCR - GCSE Maths - Question 21 - 2018 - Paper 2
Step 1
Write down an expression for the area of the larger circle
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Answer
The area of the larger circle with radius 6 cm is given by the formula:
Alarge=extπr2=extπ(6)2=36extπ.
Step 2
Write down an expression for the area of the smaller circle
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Answer
The area of the smaller circle with radius x cm is given by:
Asmall=extπr2=extπ(x)2=extπx2.
Step 3
Calculate the shaded area
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Answer
The shaded area between the two circles is the area of the larger circle minus the area of the smaller circle:
Ashaded=Alarge−Asmall=36extπ−extπx2=extπ(36−x2).