Question

a circular plot of ground of radius 42 metres is sorrounded by a ring of grass plot . Find the width of the grass plot. If it's area is equal to that of the circular plot.

Answer 1

Hope this will help you

Answer 2

let the distance between outer circle and the centre be R
and the radius of the inner circle be r
area of the width can be determined by difference of area covered under both the circles
$\pi R^{2}$- $\pi r^{2}$=$\pi r^{2}$
implies $\pi R^{2}$=2* $\pi r^{2}$
implies R^{2}=2r^{2}
R=$\sqrt{2}$*r=1.4*42=58.8m
so width of the plot= 58.8-42=16.8m