Lab Activity-10 Class iX

Mathematics Lab Activities on Quadrilateral for class IX students, with complete observation tables, strictly according to the CBSE syllabus.

Objective:

To verify experimentally that the sum of the angles of a quadrilateral is 360º.

Material Required

Cardboard, white paper, coloured drawing sheet, cutter, adhesive, geometry box, sketch pens, tracing paper.

Procedure

1. Take a rectangular cardboard piece of a convenient size and paste a white paper on it.

2. Cut out a quadrilateral ABCD from a drawing sheet and paste it on the cardboard [see Fig. 1].

Figure 1

3. Make cut-outs of all the four angles of the quadrilateral with the help of a tracing paper [see Fig. 2]

Figure 2

4. Arrange the four cut-out angles at a point O as shown in Fig. 3.

Figure 3

5. The vertex of each cut-out angle coincides at the point O.

6. Such arrangement of cut-outs shows that the sum of the angles of a quadrilateral form’s a complete angle and hence is equal to 360º.

Observations

Measure of ∠A =125º.

Measure of ∠B = 95º.

Measure of ∠C = 75º.

Measure of ∠D =65º.

Sum [ ∠A + ∠B + ∠C + ∠D] = 360º.

Result :

With this activity we prove that sum of all angles of a quadrilateral is 360º.

Applications

This property can be used in solving problems relating to special types of quadrilaterals, such as trapeziums, parallelograms, rhombuses, etc.

Thanks for your visit
please comment below