Question

Length of a rectangle is 20cm and its breadth is 4cm when a new rectangle is formed by changing the length and breadth its perimeter decreased by 8 cm and area increased by 16cm^ find the change is length and breadth

Answer 1

Answer:

length of 1st rectangle= 20 cm

breadth of 1st rectangle= 4cm

area of 1st rectangle= l×b

= 20×4 cm

=80cm^2

perimeter of 1st rectangle=2(l+b)

= 2(20+4)cm

=48 cm

now..

length of 2nd rectangle= ?

breadth of 2nd rectangle=?

area of 2nd rectangle= l×b

80+16cm^2= lb

96cm^2= lb.........eq i

perimeter of 2nd rectangle=2(l+b)

48 -8cm= 2(l+ b)

(l+b) = 20cm.......eq ii

( l-b)^2=(l+b)^2-4lb

(l-b)=✓(20)^2-4 ×96

(l-b)=✓400-384

(l-b)=✓16

(l-b)=4.........eq iii

adding eq i and ii

l = 12

b= -8

Answer 2

l 12

b = z8

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