Construction of a triangle with two sides and included angle

Formation of a triangle when two of the sides and an angle of a triangle are known and recognizing the role of the given angle. Construction of a triangle follows SAS congruence rule for the given parameter.

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?

**Actual construction (using robocompass)