Construct a square ABCD,length of whose one side is 4 cm.

I assume you know how to construct a line perpendicular to a given line.

On line AB, mark off 4 units. Construct a perpendicular at those endpoints.
Mark off the same 4 units on each perpendicular. Label those points C and D.
Connect C and D for the 4th side

To construct a square ABCD with a side length of 4 cm, follow these steps:

Step 1: Start by drawing a straight line segment AB of length 4 cm. This will represent one side of the square.

Step 2: Using a compass, place the pointed end at point A and extend the other end to draw an arc that intersects the line AB.

Step 3: Without changing the compass width, place the pointed end at point B and draw another arc that intersects the previous arc.

Step 4: Label the point of intersection of the arcs as point C.

Step 5: Draw a line segment CD parallel to AB, and equal in length to AB, starting from point C.

Step 6: Draw a line segment DA parallel to BC, and equal in length to BC, starting from point D.

Step 7: Connect the points A, B, C, and D to form a closed square shape.

Now you have successfully constructed a square ABCD with a side length of 4 cm.