Question

If the length of the rectangle is increased by 40% and its breadth is decreased by 40%, what will be the percentage change in its perimeter?​

Answer 1

Answer:

84%

Step-by-step explanation:

Length is increased by 40% and breadth is reduced by 40%

Let length be l and breadth be b

Therefore Area1 ,A1=lb

Given:

l=l+lx40/100

=140l/100=14l/10

b=b-bx40/100

=60b/100=6b/10

Therefore,

Area2 A2=14l/10x6b/10

=84lb/100

Therefore,area increases by 84%

Answer 2

Let the unknown be 1 and 2 (example)

Let 1 be breadth
Let 2 be length

So it perimeter would be 6
According to the question

1 = 100%
= 100-40=60%

= 0.6

2= 100%
?= 100+40=140%

=2.4

So the perimeter would be 6

Hence there no change