Construction of a triangle with two sides and included angle

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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.


  • 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

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)