Question

Draw ΔABC given AB = 9 cm, ∠CAB = 115° and ∠ABC = 40°. Locate its incentre and also draw the incircle.

Answer 1

Steps for construction:

Step 1: Draw the ΔABC with AB = 9 cm, ∠B = 40° and ∠A = 115°.

Step 2: Construct the angle bisectors of any two angles (A and B) and let them meet at I. Then I is the incentre of ΔABC.

Step 3: Draw perpendicular from I to any one of the side (AB) to meet AB at D.

Step 4: With I as centre and ID as radius draw the circle. This circle touches all the sides of the triangle internally.

Step 5: Measure of In-radius = 2.7 cm.