Question

The perimeter of a rectangle becomes
perimeter, if its length and breadth are doubled.​

Answer 1

Perimeter of a rectangle whose length is l and breadth is b is

2×(l+b)

If length and breadth are doubled, they become 2l and 2b and perimeter becomes

2×(2l+2b)=2×2(l+b)=4(l+b)

i.e. perimeter is doubled.

Answer 2

Let the length of rectangle = L

Let the breadth of rectangle = B

Perimeter of rectangle = 2(length + breadth)

Perimeter = 2(L + B) ----- (1)

when length is doubled = 2L

when breadth is doubled = 2B

Perimeter = 2(2L + 2B)

Perimeter = 2× 2 (L + B) ------ (2)

From (1) and (2)

Perimeter of a rectangle when its length and breadth are doubled = 2× Perimeter of rectangle