Question

If the length and breadth of a rectangle are doubled, how does its perimeter change?

• A. Tripled
• B. Doubled
• C. Halved
• D. Becomes 4 times

Answer 1

The correct option is B

Doubled

Perimeter of the old rectangle is, $p=2(l+b)$

The new length and breadth of the rectangle now is,
$l^{\prime }=2l;b^{\prime }=2b$
Perimeter of new rectangle, $p^{\prime }=2(l^{\prime }+b^{\prime })$
$p^{\prime }=2(2l+2b)=2\times 2(l+b)=2p$