Mathematics Lab Activity-10 Class IX | Quadrilateral

  Lab Activity-10 Class iX

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

Chapter - 08  quadrilateral

Activity - 10

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.

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