Question

length of a rectangle is 3 times it's breath . if perimeter of rectangle is 40 cm,find its area​

Answer 1

Answer:

Perimeter of a rectangle = 2(length + breadth)

Let the breadth of the rectangle be x.

So length of the rectangle will be 3x.

=> 2(3x+x) = 40 cm

=>2(4x) = 40 cm

=> 8x = 40cm

Therefore x= 40/8 = 5

So the breadth of the rectangle is 5 cm and the length is (3x=3*5) 15 cm.

Step-by-step explanation:

Cross check

Perimeter= 2( l+ b)

=>2(5+15)

=>2*20= 40cm.

Answer 2

Answer:

The area of the rectangle is 75 cm².

Step-by-step explanation:

Let the breadth (b) of the rectangle be 'x'

Then the length (l) of the rectangle is '3x'

The given value of the perimeter is 40 cm

The question is to find the area of the rectangle.

To find the area of the rectangle, the 'x' value should be known.

The perimeter (P) of the rectangle is the sum of all four sides or we can use the following formula.

       P = 2(l + b)

Now substitute the values to find 'x'

⇒      40 = 2(3x + x)

             = 2(4x)

             = 8x

Hence the breadth, x = 40 ÷ 8

                            = 5 cm

Therefore the length, 3x = 3 × 5 = 15 cm

The area (A) of the rectangle can be found by multiplying the length and breadth. That is,

         A = lb

 By substituting,

        A = 15 × 5 = 75 cm²