Question 710796
All the angles of a rectangle are right angles.
A right angle inscribed in a circle intersects the circle at the ends of a diameter.
As a consequence, the diagonals of the rectangle are diameters of the circle it is inscribed in.
AC and BD are those diagonals/diameters.
Their lengths are
AC={{{sqrt((-2-3)^2+(-6-(-1))^2)=sqrt(5^2+(-6+1)^2)=sqrt(5^2+5^2)=sqrt(2*5^2)=highlight(5sqrt(2))}}}
{{{drawing(300,300,-5,5,-8,2,
grid(1),
blue(line(-2,-6,4,-3)),blue(line(4,-3,3,-1)),
blue(line(3,-1,-3,-4)),blue(line(-3,-4,-2,-6)),
blue(circle(0.5,-3.5,5*sqrt(2)/2)),
locate(-2.5,-6,A(-2,-6)),locate(3.1,-0.5,C(3,-1)),
red(triangle(-2,-6,3,-1,3,-6)),red(rectangle(3,-6,2.8,-5.8))
)}}}