Construction of a triangle with 3 sides

This activity shows how to construct a triangle when the three sides of a triangle are known.

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
.
.

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?

**Actual construction (using robocompass)