Q11 of 99 Page 264

Sujata will draw a rectangular picture on a paper with area 84 sq. cm. The difference of length and breadth of paper is 5 cm. Let us calculate the perimeter of paper of Sujata.

Let length be L, breadth be B.


We know, area of rectangle = length × breadth


Given, Area of rectangular picture = 84 cm2


⇒ L × B = 84cm2


Also, Given the difference of length and breadth is 5 cm.


⇒ L - B = 5cm


Or L = B + 5


Substituting, (B + 5) × B = 84


B2 + 5B - 84 = 0


B2 + 12B - 7B - 84 = 0


B(B + 12) - 7(B + 12) = 0


(B - 7)(B + 12) = 0


B cannot be negative, so B = 7cm.


L = 12cm


Perimeter of a rectangle = 2(L + B)


= 2(12 + 5) = 34cm


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