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Hi Brooklyn, You would need to know a combination of any two of the following: length, width, perimeter, area. Obviously, if you know the length and width you're set! You can calculate the perimeter using P=2L +2W and you can calculate the area using A = LW If you know the area and either length or width, you can use the area formula to determine the other dimension: If you know the perimeter and either length or width, you can use the perimeter formula to determine the other dimension: If you know both the area and the perimeter, you can also determine the dimensions, but it takes a little more work and involves either guessing and checking (which may prove difficult or impossible if any dimension is irrational) or solving a quadratic equation. Given A = 15, P = 16 15 = L(8  L) We would choose L = 5 (only because by convention we think of the length being the longer side) and by substitution into one of our original equations we find the width is 3. Hope this helps,
 


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