Question 571215
<pre>
That's not enough information.

To show that it isn't, draw a circle with diameter 8:


{{{drawing(200,200,-1,1,-1,1, circle(0,0,1) )}}}

Inscribe some rectangles:

{{{drawing(200,200,-1,1,-1,1, circle(0,0,1),
rectangle(cos(210*pi/180),sin(210*pi/180), cos(30*pi/180),sin(30*pi/180)),
triangle(0,0,cos(210*pi/180),sin(210*pi/180),cos(30*pi/180),sin(30*pi/180)),
triangle(0,0,cos(210*pi/180),-sin(210*pi/180),cos(30*pi/180),-sin(30*pi/180))


 )}}}{{{drawing(200,200,-1,1,-1,1, circle(0,0,1),
rectangle(cos(255*pi/180),sin(255*pi/180), cos(75*pi/180),sin(75*pi/180)),
triangle(0,0,cos(255*pi/180),sin(255*pi/180),cos(75*pi/180),sin(75*pi/180)),
triangle(0,0,cos(255*pi/180),-sin(255*pi/180),cos(75*pi/180),-sin(75*pi/180))


 )}}}{{{drawing(200,200,-1,1,-1,1, circle(0,0,1),
rectangle(cos(185*pi/180),sin(185*pi/180), cos(5*pi/180),sin(5*pi/180)),
triangle(0,0,cos(182*pi/180),sin(185*pi/180),cos(5*pi/180),sin(5*pi/180)),
triangle(0,0,cos(182*pi/180),-sin(182*pi/180),cos(5*pi/180),-sin(5*pi/180))


 )}}}{{{drawing(200,200,-1,1,-1,1, circle(0,0,1),
rectangle(cos(225*pi/180),sin(225*pi/180), cos(45*pi/180),sin(45*pi/180)),
triangle(0,0,cos(225*pi/180),sin(225*pi/180),cos(45*pi/180),sin(45*pi/180)),
triangle(0,0,cos(225*pi/180),-sin(225*pi/180),cos(45*pi/180),-sin(45*pi/180))


 )}}}

All these rectangles have diagonal 8, because the diagonals are 
all diameters of the circle, yet they all have different size sides.

Edwin</pre>