Using ruler and compasses only, draw an equilateral triangle of side 5 cm. Draw its inscribed circle. Measure the radius of the circle.

Steps of construction :

1. Draw a line segment BC = 5 cm.

2. With centers B and C, draw two arcs of 5 cm intersecting each other at A.

3. Join AB and AC.

4. Draw angle bisectors of ∠B and ∠C intersecting each other at O.

5. From O, draw perpendicular OL to BC.

6. With O as center and OL as radius draw a circle, touching sides of △ABC. Measure OL.

On measuring,

OL = 1.4 cm.

Hence, above is the required incircle of △ABC with radius = 1.4 cm.