Question:
Construct a square of side 4 cm.
Solution:
Steps of construction:
1. Draw a line segment AB = 4 cm.
2. Construct $\angle B A X=90^{\circ}$ and $\angle A B Y=90^{\circ}$.
3. Set off AD = 4 cm and BC = 4 cm.
4. Join DC.
Thus, $\square A B C D$ is the required square.