Question

if the length and breath of a rectangle are doubled how many times the perimeter of the old rectangle will that of the new rectangle be??


plz answer me with solution.

Answer 1

$let \: original \: length \: and \: breadth \: be \: l \: and \: b$
$thus \: new \: dimensions \: are \: 2b \: and \: 2l$
$thus \: initial \: perimeter \: is \: 2(l + b) \\ final \: perimeter \: is \: 2(2l \: + 2b) = 2(2(l + b)) \\ \: \: \: \: \: \: \: = 4(l + b)$
thus initial perimeter is 2 times less than new one

Answer 2

Let the old rectangle's length be L and breath be B
Perimeter, P1 = 2(L+B). ______(1)


When Length and breath is doubled length and breath will be 2L and 2B respectively

Perimeter, P2 = 2(2L+2B)
P2 = 4(L+B). ______(2)
dividing equation (2) by (1)
we get,
P2/P1 = 4(L+B)/2(L+B)
P2=2×P1
The new rectangle will be 2 times the old rectangle