# Construction of a triangle with 3 sides

From Karnataka Open Educational Resources

Investigating formation of a unique triangle with the given parameters as the three sides. Constriction follows SSS congruence rule.

## Contents

### Objectives

- To construct a triangle for given 3 sides
- To show formation of different types of triangles when sides are varied
- To show changes in angles when sides are varied.
- To show possibility of formation of a triangle

### Estimated Time

30 minutes

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

Prior understanding of point, lines and angles, elements of triangle, properties of triangle

### Materials/ Resources needed

- Digital : Computer, geogebra application, projector.
- Non digital : Worksheet and pencil
- Geogebra files : "Triangle construction (3sides)"

Download this geogebra file from this link.

### Process (How to do the activity)

- Use the geogebra file to demonstrate how to construct a triangle if three sides of a triangle are given
- Students can be asked for a given any one side how many triangles are possible.
- How will you draw the second side? Where will you fix the position of the second side?
- How will you draw the third side? How can you fix the position third side?
- For what measurement of sides the triangle is not possible.
- Vary the sliders to observe the changes reflected in the triangle.
- Make different types of triangles with respect to sides by changing the sliders.
- Challenge them to make
- Isosceles right angled triangle,
- Equilateral triangle including right angle or obtuse angle

- Note the measure of sides in the worksheet

**Work sheet**

Side1 | Side2 | Side3 | Side1+ Side2 > Side 3 | Side2 + Side 3 > Side 1 | Side1+ Side3 > Side 2 | YourObservations |

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**Evaluation at the end of the activity**

- Can you construct a triangle for any given sides?
- For given 3 sides how many triangles are possible?
- Will the triangle formed change if the order of sides taken for construction is changed?