Page 173 - Start Up Mathematics_5
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Example 1:      Find the perimeter of a rectangle whose length is 12 cm and breadth is 7 cm.


            Solution:       Length (l) = 12 cm, Breadth (b) = 7 cm            A Challenge!
                            Perimeter = 2 × (l + b)                            The perimeter of a rectangle

                                       = 2 × (12 cm + 7 cm)                     is 24 cm. If its length is
                                                                               7 cm, find its breadth.
                                       = 2 × 19 cm = 38 cm


            Perimeter of a square                                                                   side

            Perimeter of square DEFG = DE + EF + FG + GD                                    D                E
                                         = Side + Side + Side + Side

                                         = 4 × Side                                         side                side

                   Perimeter of a square = 4 × Side                                         G                F
                                                                                                   side
                   Side of a square =   Perimeter
                                             4



            Example 2:      Find the perimeter of a square whose sides measure 6 cm each.

            Solution:       Side = 6 cm
                            Perimeter = 4 × Side

                                       = 4 × 6 cm = 24 cm

            Example 3:      Find the measure of the side of a square whose perimeter is 48 cm.

            Solution:       Perimeter = 48 cm

                            Side =  Perimeter
                                        4

                                 =  48   cm = 12 cm
                                     4

            Perimeter of a triangle                                                                    L

            Perimeter of triangle LMN = LM + MN + NL
                                         = a + b + c                                            a            c


              Perimeter of a triangle = Side + Side + Side
                                                                                            M         b        N
            Example 4:      Find the perimeter of a triangle whose sides measure 4 cm, 6 cm and 5 cm.

            Solution:       a = 4 cm, b = 6 cm, c = 5 cm

                            Perimeter = a + b + c
                                       = 4 cm + 6 cm + 5 cm = 15 cm




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