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SAI International School
                                                       CLASS - VIII


                  Mathematics
                  CHAPTER-11 :Mensuration                                     Lesson Notes-1


                  SUBTOPICS: Introduction


                  Introduction:
                  Mensuration deals with length, area and volume of different kinds of shape- both 2D
                  and 3D. It is based on the use of algebraic equations and geometric calculations to
                  provide measurement data regarding the width, depth and volume of a given object
                  or group of objects. While the measurement results obtained by the use of
                  mensuration are estimates rather than actual physical measurements the
                  calculations are usually considered very accurate.


                  There are two types of geometric shapes: 2D and 3D

                  2D shapes are: Square, Rectangle, Parallelogram, Rhombus, Triangle, Trapezoid,
                  Circle


                  3D shapes: They have surface area and volume.

                  Cube, Cuboids, Cylinder, Cone, Sphere, Prism, Pyramid.

                  Example : A square and a rectangular field with measurements as given in the figure
                  have the same perimeter. Which field has a larger area?
















                  Solution:
                  Given: The side of a square = 60 m
                  And the length of rectangular field = 80 m
                  According to question,
                  Perimeter of rectangular field = Perimeter of square field
                  => 2(l + b) = 4 * side
                  => 2(80 + b) = 4 * 60
                  => 160 + 2b = 240
                  => 2b = 240 – 160
                  => 2b = 80

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