Question

Construct a square given one of its diagonals.

Answer 1

let the diagonal be AB.Draw a perpendicular bisector PQ to the diagonal AB cutting it at O.With O as a center and radius 1/2 AB,draw arcs cutting PQ at C &D on one side & other side AB,respectively.
JOIN AC,AD,BC&BD.
HERE IS YOUR SQUARE ABCD.

Answer 2

ok, thanks.