Let x = width
2x = length as given in the description
Area of a rectangle is length * width so we do:
2x(x) = 18
2x² = 18
Divide by 2 to isolate our variable:
x² = 9
√x² = √9
x = 3
Length = 6, width = 3
Perimeter = (Length * 2) + (Width * 2)
We plug in our new information to find the perimeter.
P = (6*2) + (3*2)
= 12 + 6
= 18
The perimeter of the rectangle is 18 centimeters. Ironically, matching its area.