Question

If the length of the rectangle is increased by 40% and it's breadth is decreased by 40% , what will be the percentage change in it's perimeter

Answer 1

Step-by-step explanation:

let L be length and B be breadth of the rectangle

A = L*B ( area before change)

length after change is 1.4L and breadth is 0.6B

A' = 1.4L*0.6B = 0.84LB ( new area)

change in area = A - A' ( A > A')

= LB - 0.84LB = 0.16LB

% decrease =( 0.16LB*100)/LB = 16% decrease

Answer 2

Answer:

let length be 1000

breadth be 100

so perimeter is 2*(100+ 1000)= 2200

on changing perimeters,

new length is 1400

new breadth is 60

new perimeter is 2*(1400+60)= 2920

so change is

2920- 2200= 720

720/2200*100= 32.72%

Step-by-step explanation: