Question 835146
{{{drawing(750/3,300,-6,4,-2,10,

grid(1),

circle(-1,4,0.15),circle(-1,4,0.13),circle(-1,4,0.11),circle(-1,4,0.09),circle(-1,4,0.07),circle(-1,4,0.05),circle(-1,4,0.03),circle(-1,4,0.01),
line(2,7,-3,5),
circle(-3,5,0.15),circle(-3,5,0.13),circle(-3,5,0.11),circle(-3,5,0.09),circle(-3,5,0.07),circle(-3,5,0.05),circle(-3,5,0.03),circle(-3,5,0.01),
locate(-3.1,5,F),

circle(2,7,0.15),circle(2,7,0.13),circle(2,7,0.11),circle(2,7,0.09),circle(2,7,0.07),circle(2,7,0.05),circle(2,7,0.03),circle(2,7,0.01),


locate(-1.4,4,D),locate(1.6,7,E) )}}} 

Since the diagonals of a parallelogram bisect each other we know 
that ED is half a diagonal.  So we draw in half-diagonal ED.

{{{drawing(750/3,300,-6,4,-2,10,
green(line(2,7,-1,4)),
grid(1),

circle(-1,4,0.15),circle(-1,4,0.13),circle(-1,4,0.11),circle(-1,4,0.09),circle(-1,4,0.07),circle(-1,4,0.05),circle(-1,4,0.03),circle(-1,4,0.01),
line(2,7,-3,5),
circle(-3,5,0.15),circle(-3,5,0.13),circle(-3,5,0.11),circle(-3,5,0.09),circle(-3,5,0.07),circle(-3,5,0.05),circle(-3,5,0.03),circle(-3,5,0.01),
locate(-3.4,5,F),

circle(2,7,0.15),circle(2,7,0.13),circle(2,7,0.11),circle(2,7,0.09),circle(2,7,0.07),circle(2,7,0.05),circle(2,7,0.03),circle(2,7,0.01),


locate(-1.4,4,D),locate(1.6,7,E) )}}}

Going from E to D is going left 3 units and down 3 units, so to
extend the half diagonal to finish the full diagonal EG, from D we go 
left 3 units and down 3 units, and arrive at (-4,1), and label it G.
Then we draw side FG 

{{{drawing(750/3,300,-6,4,-2,10,
green(line(2,7,-4,1)),locate(-3.8,1,G),
grid(1),

circle(-1,4,0.15),circle(-1,4,0.13),circle(-1,4,0.11),circle(-1,4,0.09),circle(-1,4,0.07),circle(-1,4,0.05),circle(-1,4,0.03),circle(-1,4,0.01),
line(2,7,-3,5),
circle(-3,5,0.15),circle(-3,5,0.13),circle(-3,5,0.11),circle(-3,5,0.09),circle(-3,5,0.07),circle(-3,5,0.05),circle(-3,5,0.03),circle(-3,5,0.01),
locate(-3.3,5,F),

circle(2,7,0.15),circle(2,7,0.13),circle(2,7,0.11),circle(2,7,0.09),circle(2,7,0.07),circle(2,7,0.05),circle(2,7,0.03),circle(2,7,0.01),

line(-4,1,-3,5),
circle(-4,1,0.15),circle(-4,1,0.13),circle(-4,1,0.11),circle(-4,1,0.09),circle(-4,1,0.07),circle(-4,1,0.05),circle(-4,1,0.03),circle(-4,1,0.01),

locate(-1.4,4,D),locate(1.6,7.7,E) )}}}

We could finish by doing the same with the other diagonal. 
But we can also just realize that going from F to E is 
going right 5 units and up 2 units. So to find the point H,
from G we go right 5 units and up 2 units, and arrive at 
(1,3), and label it H. Then we draw sides GH and HE.

{{{drawing(750/3,300,-6,4,-2,10,
green(line(2,7,-4,1)),locate(-3.8,1,G),
grid(1),

circle(-1,4,0.15),circle(-1,4,0.13),circle(-1,4,0.11),circle(-1,4,0.09),circle(-1,4,0.07),circle(-1,4,0.05),circle(-1,4,0.03),circle(-1,4,0.01),
line(2,7,-3,5),
circle(-3,5,0.15),circle(-3,5,0.13),circle(-3,5,0.11),circle(-3,5,0.09),circle(-3,5,0.07),circle(-3,5,0.05),circle(-3,5,0.03),circle(-3,5,0.01),
locate(-3.5,5.7,F),

circle(2,7,0.15),circle(2,7,0.13),circle(2,7,0.11),circle(2,7,0.09),circle(2,7,0.07),circle(2,7,0.05),circle(2,7,0.03),circle(2,7,0.01),
line(-4,1,1,3),line(1,3,2,7),locate(1.2,3,H),
line(-4,1,-3,5),
circle(-4,1,0.15),circle(-4,1,0.13),circle(-4,1,0.11),circle(-4,1,0.09),circle(-4,1,0.07),circle(-4,1,0.05),circle(-4,1,0.03),circle(-4,1,0.01),

locate(-1.4,4,D),locate(1.6,7.7,E) )}}}

So G is (-4,1) and H is (1,3)

Edwin</pre>