Steps of construction :
(1) Construct a △ABC with the given data.
(2) Draw the internal bisectors of ∠B and ∠C. Let these bisectors cut at O.
(3) Taking O as centre. Draw a incircle which touches all the sides of the ∆ 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=1.5‌cm‌. (app.) ‌