Question 1105674
I do not know exactly what the kite in the drawing you had looks like,
but a kite like the one described, and its diagonals is sketched below in black.
The rectangle it would fit in is drawn in red,
and the rectangle connecting the midpoints of the kite's side is drawn in green.
{{{drawing(320,500,-64,64,-130,70,
triangle(-56,0,56,0,0,60),
triangle(-56,0,56,0,0,-120),
triangle(0,-120,56,0,0,60),
red(rectangle(-56,-120,56,60)),
green(rectangle(-28,-60,28,30)),
locate(-60,3,A),locate(57.5,3,C),
locate(-1,66,B),locate(-1,-120,D),locate(1.5,0,O)
)}}}
 
The measures of the sides of the red rectangle are
{{{AC=56cm}}} and {{{BD=90cm}}} .
 
The short sides of the green rectangle
midsegments of triangles ABC and ACD, parallel to side AC, so their length is
{{{(1/2)AC=(1/2)(56cm)}}} .
 
The long sides of the green rectangle
midsegments of triangles BCD and ABD, parallel to side BD, so their length is
{{{(1/2)BD=(1/2)(90cm)}}} .
 
The perimeter of the green rectangle is
{{{56cm+90cm=highlight(146cm)}}} ,
and that is the length of ribbon needed.
 
The green rectangle is a 1/2 scale version of the red one,
independent of the ratio of lengths {{{OB/OD}}} .