1.The square READ with RE = 5.1 cm.

Construction:



Step 1: Draw RE = 5.1 cm.

Step 2: Draw an angle of \(90^{\circ}\) at E and cut an arc EA = 5.1 cm.

Step 3: Draw two arcs from A and R with radius 5.1 cm to cut each other at D.

Step 4: Join RD and AD.

Hence we have, READ as the required square.