so the length is 4*28=112mm
The width would be calculated like this:
you draw an equilateral triangle in the middle with sides or 2r(56mm). The based on pythagorean theorem u know that
h=rad(56^2-28^2)=48.497
28+28+h=104.497
The area would be S=l*w which is 11703.7113mm
