Length + width = half the perimeter, but more info eg area, is needed.
In general you cannot find the perimeter of any shape if only the area is given.
Assuming that you want to minimise the perimeter, then use a square. Its side length is, of course, given by the square root of the area.
If you are given the width and the perimeter, then figure out what the length is then calculate the area... hope this helps :)
You cannot.
Perimeter = 4*Side so that Side = Perimeter/4 Area of a rhombus = Side * Altitude so Altitude = Area/Side = Area/(Perimeter/4) = 4*Area/Perimeter
Knowing only the area, there is no way to find the dimensions without significantly more information.
You cannot. For a given area, an equilateral triangle will have the smallest perimeter but that perimeter can be increased - without limit - without increasing the area.
Unless the area is a regular polygon (or a circle) you cannot.
Just add together the 4 given dimensions to find the perimeter of the room.
There are often multiple 'correct' dimensions for these problems. The most straight forward way to solve it is to list all the factors that, when multiplied, equal the area. Then from this list, cross out the factors that DON'T equal your perimeter. The remaining factors are your possible dimensions.
If you are given the area you will have to think what do you times with the number you have to get it.