The hypotenuse of such a right triangle is sqrt(2) times the length of one of

the other sides.

So going from the side of length x clockwise the sides radiating from the

central point have lengths:

x,

x sqrt(2),

sqrt(2) (x sqrt(2)),

sqrt(2) (sqrt(2) (x sqrt(2))),

sqrt(2) (sqrt(2) (sqrt(2) (x sqrt(2))))

but this last one we are told is 4, so:

sqrt(2) (sqrt(2) (sqrt(2) (x sqrt(2)))) = 4x = 4,

so x=1.

RonL