The perimeter of a rectangle is 48 centimeters. The relationship between the length, the width, and the perimeter of the rectangle can be described with the equation 2 . length+2 . width=48. find the length in centimeters if width is w centimeters. Although written poorly, the obvious is stated...."the perimeter of the rectangle can be described with the equation 2length + 2width = 48." With width being w, and length, L, we get: 2w + 2L = 48 2(w + L) = 2(24) w + L = 24 Length, or L = 24 - w.