Question

18. The breadth of a rectangle is 4 cm less than its length. If the length is increased by 4 cm and the
breadth is decreased by 1 cm, the area of the rectangle is increased by 40 cm2 . Find the length and breadth of the rectangle.​

Answer 1

Answer:

Let the length be l and breadth be b

Original area of the rectangle=l*b

Given l=b+4

When the length is increased by 4cm,new length=l+4

When the breadth is decreased by 2 cm ,new breadth=b-2

(l+4)(b-2)=lb [given the area remains same]

lb-2l+4b-8=lb

-2l+4b=8 [lb get cancelled on both sides]

-l+2b=4 [dividing by 2}

-b-4+2b=4 [l=b+4 therefore -l=-(b+4)=-b-4]

b=8 cm

l=4+8=12 cm