# Congruence in triangles – SSS Rule

From Karnataka Open Educational Resources

Investigating the possibility of congruence if three sides of two triangles are congruent.

### Objectives

Compare sides in triangles to check for congruence

### Estimated Time

30 minutes

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

Prior knowledge of point, lines, angles, closed figures

### Materials/ Resources needed

- Digital : Computer, geogebra application, projector.
- Non digital : Worksheet and pencil, triangles of same and different shapes
- 3. Geogebra files : “
**SSS congruence.ggb**”

Download this geogebra file from this link.

### Process (How to do the activity)

Prior hands on activity

- Three triangles are distributed to groups of students.
- Children should identify the triangles that are congruent.
- They can name the vertices in the given triangles.
- Write down the sides and angles that are coinciding in the two triangles.

Use the geogebra file

- How many triangles you observe?
- Are all the triangles same, point out the triangles that are same.
- How can you say they are same? What can you do to check if the two triangles are congruent?
- What parameters of triangles are required to know if they are congruent?
- What about the third triangle is it the same as the other two, what you should do to show the triangle is same as the others – concept pf reflection can be discussed

HW:

- Make two triangles of same sizes. Cut it and verify they are congruent.
- Construct one triangle – Base = 3, 4 and 5 are other sides. Another triangle base = 5; and two sides are 3 and 4. Another triangle base = 4; and two sides are 3 and 5. Does the order of sides matter in a triangle?

**Evaluation at the end of the activity**

- Students should be able to understand, if 3 corresponding sides of two triangles are same then the triangles are congruent.
- Students should also understand that the sequence of sides examined in the triangles need not be same for the triangles to be congruent.