r^2:2π/π=2

R= root number 2

Circumference: 2π* root number 2

Square:

Side length: root sign (2*π)

Perimeter: 2* root π * root 2

The circumference of an obvious circle is larger (because π >; Radical π)

The enlightenment is that the circumference of a circle and a square circle with the same area is large.