# Construction of a triangle with two sides and included angle

From Karnataka Open Educational Resources

Construing of a triangle when two of the sides and an angle of a triangle are known and recognizing the role of the given angle, this construction follows SAS congruence rule for the given parameters.

### Objectives

- To construct a triangle given two sides and an angles
- To understand the given angle should be included angle when two sides are given

### Estimated Time

20 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 (2sides-1angle)"

Download this geogebra file from this link.

### Process (How to do the activity)

- For given angles and sides, which parameter will you start the construction with.
- If the given angle is drawn first what are the next steps of construction.
- How many triangles are possible if the triangle is drawn such that the given angle is not included angle ( - if the second side is not marked along the arm of the angle but from point B)
- If you start the construction with a given side which of the other two parameters should be taken next to complete the required triangle.

**Evaluation at the end of the activity**

- How many triangles are possible for given 2 sides and an angle?
- What is the additional condition that is required to be specified if 2 sides and 1 angle is given for constructing a triangle?