Steps of construction : (1) Construct a $\triangle ABC$ with the given data. (2) Draw the internal bisectors of $\angle B$ and $\angle C$. Let these bisectors cut at $O$.(3) Taking $O$ as centre. Draw a incircle which touches all the sides of the $\Delta$ $ABC$.(4) From O draw a perpendicular to side BC which cut at $N$.(5) Measure ON which is required radius of the incircle.$ON = 1.5 \text{cm} \; \text{ (app.) } \;$