Question

Length of a rectangle is 3 times its breadth. Perimeter of the rectangle is 40 cm. Find its
length and breadth. Plz explain the answer

Answer 1

let ,

breadth be x and

length be 3x,

so ,

perimeter of rectangle=AB+BC+CD+DA

40=3x+x+3x+x

40=8x

x=40/8

x=5cm

length=3x=5×3=15

breath=x=5

Answer 2

Given,

Length of a rectangle is three times of it's breadth.

So, length $=3\times$ (breadth)

Perimeter of a rectangle $=40cm$.

Let, the length be '$l$' and breadth be '$b$'.

So, according to the given information: $l=3b$.

Formula for perimeter of a rectangle $=2(l+b)$.

$\implies 40 = 2\times [(3b)+b]$     (Since, perimeter $=40cm$ and $l=3b$)

$\implies 40 = 2\times[4b]$

$\implies 40 = 8b$

$\implies b= \frac {40} {8}$

$\implies b=5$.

So, breadth is $5cm$.

Then, length $=3b=3\times5=15cm$.

Hence, length and breadth of the given rectangle is $15cm$ and $5cm$ respectively.