Question

Construct $\Delta$PQR with QR = 6.5 cm, PQ= 5.5 cm, PR = 5 cm. Draw the incircle of $\Delta$PQR and find its radius.

• A. 4.6 cm
• B. 1.6 cm
• C. 2.8 cm
• D. 3.2 cm

Answer 1

The correct option is B

1.6 cm

1. Draw QR = 6.5 cm

2. With Q as centre, draw an arc of radius 5.5 cm = PQ and with R as centre, draw one more arc of radius 5cm (=PR). Let these arc intersect each other at point P.

3. Draw bisectors of PQR and PRQ, which meet each other at point O.

4. Through point O, draw OP $\perp$ BC.

5. With O as centre and OA as radius, draw the required incircle which will touch all the three sides of the triangle.

6. Measure OA, the radius of the incircle

7. Radius of incircle = 1.6 cm