Question

The lenght of a rectangle is twice its width. The area of the rectangle is 18 square centimeters. Find the perimeter of the rectangle?

Answer 1

Answer: 18cm

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Step-by-step explanation:
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Width = W
Length = 2W
Area = 18 cm²

Area = Length x Width
18 = 2W x W
18 = 2W²
W² = 18 ÷ 2 = 9
W = √9
W = 3

Perimeter = 2(Length + Width) = 2(3 + 2(3)) = 2(9) = 18 cm

Answer 2

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.