From ab= 12ac=cd=cb, b= 12c, 12=d, d=b, that is,12a = b =12c = d.

If it is a closed quadrilateral, it is a rectangle with length b and width a, perimeter 2(a+b) and area ab;

If the small circle is inscribed, its diameter is a, its circumference is aπ, and its area is (a/2) (a/2) π;

If the great circle is circumscribed, its diameter is the diagonal of a rectangle, and its radius is set to r, 2r * 2r= a * b * b, that is, r = root number (a*a*b*b)/2, perimeter 2rπ=π* root number (a*a*b*b), and area r * r * π = a *.