Ans. Yes, we can construct a square if we know the length of its diagonal. This is known as the diagonal method. To construct a square using the diagonal method, draw the diagonal of the square using a ruler. Then, place the compass on one endpoint of the diagonal and draw an arc that intersects the diagonal. Without changing the compass width, place the compass on the other endpoint of the diagonal and draw another arc that intersects the diagonal. Connect the two points where the arcs intersect the diagonal to form a side of the square. Repeat this process for the other three sides of the square.