# Angular bisectors and incenter of a triangle

From Karnataka Open Educational Resources

The intersecting point of three lines which are the bisectors of three angles of a triangle that is the incenter and it's properties are examined.

### Objectives

Introduce angular bisectors in a triangle and their point of concurrence.

### Estimated Time

40 minutes.

### Prerequisites/Instructions, prior preparations, if any

Angles, angle bisectors , concurrent lines and triangles should have been covered.

### Materials/ Resources needed

Digital resources: Laptop, projector and a pointer.

Geogebra file: Concurrency of angular bisectors.ggb

Download this geogebra file from this link.

### Process (How to do the activity)

- The teacher can use this geogebra file and ask the questions listed below.

- Developmental Questions;

- What type of triangle is this ? Why ?
- Identify the three angles.
- What is an angle bisector ?
- Identify the point of concurrence of angle bisectors ?
- This point, called incentre of the triangle does its position change with the type of triangle ?
- Identify the circle. What is its radius ? What can this radius be called ?
- What is this circle called ?

- Evaluation:

- What is incentre, inradius and incircle ?

- Question Corner:

- What do you think would be the practical applications of the incentre and incircle ?