Question

The length of a rectangle is 3cm longer than its width.If the perimeter of the rectangle is 54cm,find its length in cm.​

Answer 1

Length = 15cm

Explanation:

let width be x

length = x+3

Perimeter = 2(l + b)

Perimeter = 54cm

equating:

2(x + x + 3) = 54

2(2x +3) = 54

4x + 6 = 54

4x = 54 - 6

4x = 48

x = 48/4 = 12

width = x = 12cm

length = x +3 = 12 + 3 = 15cm

Answer 2

length = 15 cm

Width = 12 cm

Explanation:

Let width = w cm

Length = w + 3

Perimeter of rectangle = 54 cm

2 * (length + width) = 54

2 * (w+3 + w) = 54 {Add like terms}

2 *(2w + 3) = 54

2*2w + 2 * 3 = 54

4w + 6 = 54

Subtract 6 form both sides

4w = 54 - 6

4w = 48

Divide both sides by 4

w = 48/4

w = 12 cm

Length = 12 + 3= 15 cm