Let the radius of circle is 'r' and a side of a square is 'a',
then given condition
2πr = 4a
⇒ a = πr/2
∴ Area of square = (πr/2)2 = π2 /4r2 = 9.86r2/4 = 2.46r2
and area of circle = πr2 = 3.14;r2
and let the side of equilateral triangle is x.
Then, given condition,
3x = 2πr
⇒ x = 2πr/3
∴ Area of equilateral triangle = √3/4 x 2
= √3/4 x 4π2r2/9
= π2/3√3r2
= 1.89r2
Hence, Area of circle > Area of square > Area of equilateral triangle.