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The perimeter of a square and rectangle is the same. The width of the rectangle is 6cm and it's area is 16cmsquare less than the area of the square. Find the area of the square

Sagot :

Answer:

Area of  square = 100 square cm

Step-by-step explanation:

Let the sides of a square be = a

Perimeter of a square = 4a

Let area of square = [tex]a^2[/tex]

Let the Length of rectangle be = [tex]l[/tex]

Given: width of the rectangle = 6 cm

Area of rectangle = length x breadth

          Perimeter of rectangle and square is equal.

          That is,

                     [tex]2(length + width) = 4a\\\\2(l + 6) = 4a\\\\l + 6 = 2a\\\\l = 2a - 6[/tex]

Therefore ,

    Area of rectangle

                              [tex]= Length \times width \\\\= (2a - 6) \times 6\\\\=6(2a - 6)[/tex]

Given area of rectangle is 16 less than area of square.

That is ,

         [tex]( 6(2a- 6) ) = a^2 - 16\\\\12a - 36 = a^2 - 16\\\\a^2 - 12a +20= 0\\\\a^2 - 2a -10a + 20 = 0\\\\a(a - 2) - 10(a - 2) = 0\\\\(a -10) ( a-2) = 0\\\\a = 10 , \ a = 2[/tex]

Check which value of 'a ' satisfies the equation:

[tex]\underline {when \ a = 2 }\\\\Length\ of \ rectangle \ l = 2a - 6 = 2 ( 2 ) - 6 = 4 - 6 = - 2. \\\\Length \ cannot \ be \ negative \ number. \\\\ \underline{ when \ a = 10 }\\\\Length \ of \ rectangle \ , l = 2a - 6 = 2 (10) - 6 = 20 - 6 = 14\\\\satisfies \ the \ conditions. \\\\Therefore , a = 10[/tex]

That is , side of the sqaure = 10

Therefore , area  of the square = 10 x 10 = 100 square cm.