# Construction of a triangle with side, angle and sum of other two sides

From Karnataka Open Educational Resources

The triangle inequality states that the sum of the lengths of any two sides of a triangle must be greater than or equal to the length of the third side. Construction of a triangle with given parameters sum of two sides and an angle follows SAS congruence rule.

## Contents

### Objectives

To construct a triangle with side, angle and sum of other two sides

### 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(1side-1angle-sum of other 2 sides)”

Download this geogebra file from this link.

### Process (How to do the activity)

- Use the slider to set the base and the given angle
- The difference of the other two sides is marked using the slider
- Follow the steps for construction – step1, step2
- Students can vary the sliders to observe the changes reflected in the triangle.

**Evaluation at the end of the activity**

- When does the triangle not form?