Question

The perimeter of rectangle is 240cm if the breadth of rectangle is 40cm find its length​

Answer 1

Answer:

Length- 80cm

Step-by-step explanation:

L=? , B=40cm , Perimeter=240cm

Perimeter of rectangle=2(L+B)

240=2(L+40)

240/2=L+40

120=L+40

120-40=L

80cm=L

Answer 2

Answer:

The Perimeter of rectangle is given as 240cm.

Breadth(b) of the rectangle is given as 40cm.

We have to find the Length (l) of the rectangle.

Formula for Perimeter of rectangle = 2(Length + Breadth) =  2(l+b)

$\implies$

2(l+b) = 240

Substituting the value of b as '40'cm.

2(l+40) = 240

2l + 80 = 240

2l = 240 - 80

2l = 160

l = 80cm.

$\red\bigstar$ Length(l) of the rectangle = 80cm.

The Required Rectangle is :-

$\setlength{\unitlength}{1cm}\begin{picture}(0,0)\thicklines\multiput(0,0)(5,0){2}{\line(0,1){3}}\multiput(0,0)(0,3){2}{\line(1,0){5}}\put(0.03,0.02){\framebox(0.25,0.25)}\put(0.03,2.75){\framebox(0.25,0.25)}\put(4.74,2.75){\framebox(0.25,0.25)}\put(4.74,0.02){\framebox(0.25,0.25)}\multiput(2.1,-0.7)(0,4.2){2}{\sf\large 80cm}\multiput(-1.4,1.4)(6.8,0){2}{\sf\large 40 cm}\put(-0.5,-0.4){\bf A}\put(-0.5,3.2){\bf D}\put(5.3,-0.4){\bf B}\put(5.3,3.2){\bf C}\end{picture}$

Let us verify

Perimeter of Rectangle =  2(l+b)

Perimeter is given as 240cm

Substituting , l = 80cm and b = 40cm.

Perimeter = 2(80 + 40) = 2 × 120 = 240cm.

Hence Verified that our answer is correct.

Perimeter of 4 Common Shapes

• Triangle = side + side + side or 3a (a is side)

• Rectangle =  2(Length + Breadth) or  2(l+b)

• Square =  4× side or 4a (a is side)

• Circle = 2πr (r is radius of circle)

$\bigstar$ Perimeter of a circle is known commonly as circumference .