A circle of circumference 4*pi*r

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Quandaries & Queries

Question from Ankith:

If the circumference of a circle is 4*pi*r, what is its area?
i) 4*pi*r^2
ii) 2*pi*r^2
iii)3*pi*r^2
iv) pi*r^2

Hi,

The circumference of a circle is $\pi$ times the diameter. What is the diameter of your circle? What is its radius?

The area of a circle is $\pi$ times the square of the radius. What is the area of your circle?

Penny







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