Why is Perimeter measured in units?
Perimeter is measured in units while area is measured in squared units. Single units’ represent one-dimensional form while squared units’ represent two-dimensional’. If it is expressed more clearly, you can see that units indicate length while area is expressed in units of length squared. For instance, perimeter is measured in meters while area in squared meters.
To explain it still more clearly, let us take an example of any shape like rectangle, circle, square or rhombic and so on. To measure the perimeter of the rectangle a string can be laid all along the edges of the rectangle. The string can be continuously distributed all along the edges until it reaches the beginning of the string and then the string is cut at that point. Now the string is taken out and straightened. If you measure the length of the string, it gives the value for the perimeter of the rectangle.
If the perimeter of a square having the side length as 2 meters can be calculated like this: The square being four sided, addition of lengths of each of its side will give the perimeter of square. This will be evaluated as 4 * 2m = 8m as square has equal sides. Whether the units are in inches or meters or kilometers or centimeters or yards perimeter adds up all the side lengths of the shape and is expressed in the same units. In the case of the circle, there will not be any question of sides but perimeter takes into the picture, its circumference.
In the case of rectangle or triangle or any other polygon, the lengths of all the sides should be given in order to calculate the perimeter. An equilateral triangle and a regular polygon can be provided with length of one side which will serve the purpose for calculating the perimeter. For example, In the case of rectangle the formula that is used for perimeter will be P = 2L + 2W. The perimeter will be expressed in the unit that was used in the length and width as well.