How do you get perimeter when you know the area?

To find the perimeter when you know the area, you typically need additional information about the shape in question, as multiple shapes can have the same area but different perimeters. For example, if you have a rectangle, knowing the area allows you to express one dimension in terms of the other, and you can then calculate the perimeter using the formula ( P = 2(l + w) ). For regular shapes like squares, you can directly derive the perimeter from the area; for example, if the area of a square is ( A ), the side length ( s ) is ( s = \sqrt{A} ), and the perimeter is ( P = 4s ). However, without knowing the specific shape or additional parameters, you cannot determine the perimeter solely from the area.