Question

Let length and breadth of the rectangle under goes a small change of 2% . Find the change in area of the rectangle​

Answer 1

here

l= l

b= b

area= l×b

now with 2% change

let l= l+2% = l+0.02l= 1.02l

b= b-2% = b- 0.02b = 0.98b

area= 1.02l × 0.98b

= 0.9996 l×b

Now difference of the two area

difference= l×b- 0.9996 l×b

= l×b(1-0.9996)

= l×b( 0.0004)

Now let x be the percentage of l×b which is = 0.0004

So, x% of l×b= 0.0004

x/100× l×b= 0.0004

x of l×b= 0.0004×100= 0.04

Thus change in area = 0.04%