Construct a regular hexagon of side 2.5 cm.

Steps of construction:

1. With O as centre and radius = 2.5 cm, draw a circle
2. Take any point A on the circumference of circle.
3. With A as centre and radius = 2.5 cm, draw an arc which cuts the circumference of circle at B.
4. With B as centre and radius = 2.5 cm, draw an arc which cuts the circumference of circle at C.
5. With C as centre and radius = 2.5 cm, draw an arc which cuts the circumference of circle at D.
6. With D as centre and radius = 2.5 cm, draw an arc which cuts the circumference of circle at E.
7. With E as centre and radius = 2.5 cm, draw an arc which cuts the circumference of circle at F.
8. Join AB, BC, CD, DE, EF and FA. Then ABCDEF is the required hexagon.