Class 09 To verify experimentally that the parallelograms on the same base and between same parallels are equal in area.

 

Activity 19

 OBJECTIVE                                                                    

To verify experimentally that the parallelograms on the same base and between same parallels are equal in area.

 MATERIAL REQUIRED

 A piece of plywood, two wooden strips, nails, elastic strings, graph paper.

 METHOD OF CONSTRUCTION

 1.   Take a rectangular piece of plywood of convenient size and paste a graph paper on it.

 2.   Fix two horizontal wooden strips on it parallel to each other [see Fig. 1].

Fig. 1

 3.   Fix two nails A1 and A2 on one of the strips [see Fig. 1].

 4.   Fix nails at equal distances on the other strip as shown in the figure.

 DEMONSTRATION

 1.   Put a string along A1, A2, B8, B2 which forms a parallelogram A1A2B8B2. By counting number of squares, find the area of this parallelogram.

2.   Keeping same base A1A2, make another parallelogram A1A2B9B3 and find the area of this parallelogram by counting the squares. 

3.   Area of parallelogram in Step 1 = Area of parallelogram in Step 2.

OBSERVATION

Number of squares in 1st parallelogram = --------------.

 Number of squares in 2nd parallelogram = -------------------.

 Number of squares in 1st parallelogram = Number of squares in 2nd parallelogram.

 Area of 1st parallelogram = --------- of 2nd parallelogram

APPLICATION

This result helps in solving various geometrical problems. It also helps in deriving the formula for the area of a paralleogram.


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