Page 1 - IX Lesson Note 1area and properties- ch 9 Area of Parallelograms and Triangles
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SAI International School
                                                      CLASS -IX

               Mathematics
               Chapter-9: Area of Parallelograms and Triangles
               Lesson Notes-1



               Sub Topic: Introduction(Area of plane closed figures, properties)

               Area of a Closed Shape

               The part of any plane which is enclosed with the closed figure is known as the Planar Region.
               And the measure of this region is called the Area of that figure. This is expressed in the form of
               numbers using any unit.









               Properties of the Area of a figure

                  If the shape and size of the two figures are the same then these are said to be congruent.
                  And if the two figures are congruent then their area will also be the same. If ∆ABC and ∆DEF
                  are two congruent figures then ar (∆ABC) = ar (∆DEF).











                  But if the two figures have the same area they need not be congruent.














                  If the two non-overlapping plane regions form a new planner region. Let Area of the square be
                  ar(S) and Area of Triangle be ar (T). So Area of the new figure is Ar (P) = ar(S) + ar (T)




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