Question

if circumference of a circle is propotioal to radius then area =radius​

Answer 1

That is, the circumference of a circle is proportional to its radius, R; double R and you double C. The factor '2 pi' is simply the constant of proportionality between C and R. So the area of a circle is proportional to R2 and pi is the constant of proportionality between the area and the radius of a circle.

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