gamjatang wrote:

There is a rectangle such that one side is two times of the other side. What is the perimeter of that rectangle?

(1) The area of that rectangle is 8

(2) The length of that rectangle is 4root5

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What is different between perimeter and length?

perimeter is the length of the closure of the rectangle, that is to say, twice the sum of length and width. The length is the length itself.

although we don't know whether length or width is the longer one, let's assume l is the longer one, w is the shorter one.

Note : l doesn't mean length and w width.(1) l*w=8, l=2w --->w= 2 and l=4 ---> perimeter= 2(l+w) = 12

-->suff

(2) since we don't know if the length is longer or the width, we can't find the width ---> can't find the perimeter ----> insuff.