Procedure - Area of the Circle is half the product of its Circumference & Radius, Class 9 Math Class 9 Notes | EduRev

Mathematics (Maths) Class 9

Created by: Indu Gupta

Class 9 : Procedure - Area of the Circle is half the product of its Circumference & Radius, Class 9 Math Class 9 Notes | EduRev

The document Procedure - Area of the Circle is half the product of its Circumference & Radius, Class 9 Math Class 9 Notes | EduRev is a part of the Class 9 Course Mathematics (Maths) Class 9.
All you need of Class 9 at this link: Class 9

As performed in real lab:

Materials required:

Coloured paper, compass, scale, a pair of scissors, gum, colours

Procedure:

  • Draw a circle of radius r = 4 cm (say) on the paper.

  • Divide the circle into 16 equal parts. [Fig (a)]

  • Cut all the 16 parts and arrange them to get the [Fig (b)].

  • Take any part from any side and further divide it into 2 parts. [Fig (c)]

  • To complete the shape of rectangle arrange these two smaller parts at the corners of the shape obtained in [Fig (b)].

  • Find the length and the breadth of the rectangle so formed [Fig (d)].

  • Find the area of the rectangle.

 

Procedure - Area of the Circle is half the product of its Circumference & Radius, Class 9 Math Class 9 Notes | EduRev

Procedure - Area of the Circle is half the product of its Circumference & Radius, Class 9 Math Class 9 Notes | EduRev
          Fig (b)


Procedure - Area of the Circle is half the product of its Circumference & Radius, Class 9 Math Class 9 Notes | EduRev

Procedure - Area of the Circle is half the product of its Circumference & Radius, Class 9 Math Class 9 Notes | EduRev
         Fig (d)

As performed in Simulator:

  • Click on scale (between 2 and 3) in workbench to draw circle.

  • Click on the circle to mark 16 sectorials parts & color them differently.

  • Move mouse over each wedge to align them in a row.

  • Click on next button below to color wedges & divide in two group.

  • Click blue group to rotate and align.

  • Drag the blue group and drop over green group to join and form parallelogram.

  • Click on left most wedge to cut it into two parts.

  • Drag the red part and attach to the right end so as to form a rectangle.

  • This is a rectangle whose area can be calculated as (Length x Breadth).

Observations:

  • The students will observe that the area of rectangle   Procedure - Area of the Circle is half the product of its Circumference & Radius, Class 9 Math Class 9 Notes | EduRev
  • The students will observe that the rectangle is obtained from parts of circle. Hence area of circle = π x r2

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