Question

20. The sides of the rectangle are in the ratio 5:4. If its perimeter is 72 cm, then its
length ? (hint, ans = 20cm]​

Answer 1

length=5x

breadth=4x

perimeter = 2(l+b)

72 = 2(5x+4x)

72=2(9x)

72=18x

x=72÷18

x=4

length=5x

= 5×4

=20

breadth=4x

= 4×4

=16

Answer 2

Answer:

• 1st side of rectangle = 20 cm

• 2nd side of rectangle = 16 cm

Given :

• The sides of the rectangle are in the ratio 5:4.

• Its perimeter is 72 cm.

To find :

• Then its length = ?

Step-by-step explanation:

Let the 1st side of the rectangle be 5x.

Then, the second side of the rectangle be 4x.

Now,

Perimeter of rectangle = 72 cm [Given]

We know that,

Perimeter of rectangle = 2( l + b)

Substituting the values in the above formula, we get,

72 = 2( l + b )

72 = 2 ( 5x + 4x)

72 = 10x + 8x

72 = 18x

Or, 18x = 72

x = 72/18

x = 4

Hence,

1st side of rectangle ,5x ➻ 5 x 4= 20 cm

2nd side of rectangle, 4x ➻ 4 x 4 = 16 cm