Method #1 – Perimeter from Length or Width
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Formula – How to calculate the perimeter of a rectangle using the length
Perimeter = Length of one side x 4
Example
A square has a side with the length of 10 inches.
Perimeter = 10 inches x 4 = 40 inches
Method #2 – Perimeter from Area
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Formula – How to calculate the perimeter of a rectangle from the area
Perimeter = 4 x √Area
Example
A square has an area of 100.
Perimeter = 4 x √100 = 4 x 10 = 40
Method #3 – Perimeter from the Diagonal
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Formula – How to calculate the perimeter of a square from the diagonal
Perimeter = 4 x (√(diagonal2 ÷ 2))
Example
A square has a diagonal with a length of 14.
Perimeter = 4 x (√(142 ÷ 2))
Perimeter = 4 x (√(196 ÷ 2))
Perimeter = 4 x √98
Perimeter = 4 x 9.899
Perimeter = 39.596