How to get the PERIMETER of a RECTANGLE

From a PROFESSOR we are happy to present a very interesting and important lesson within the world of mathematics and geometry: the rectangle and the calculation of its perimeter. For this reason, we will start by defining what a rectangle is; then we will see what is the process to calculate a perimeter of any geometric figure; and, finally, we will tell you how to find the perimeter of a rectangle which is our goal in the lesson that concerns us this time.

Index

1. What is a rectangle
2. Meaning of perimeter in mathematics
3. How to calculate the perimeter of a rectangle?
4. Exercise to find the perimeter of a rectangle (with solution)

Before discovering how to find the perimeter of a rectangle, we have to define this geometric figure. Surely you all know what a rectangle, since it is a very common figure that we can see or get practically in any environment in which let us be: on a walk, at school, at home, there are objects and things that have the shape of rectangle. However, our mission is to define it theoretically.

In this sense, a rectangle is a flat geometric figure what's wrong with it four sides, of which two are shorter and of the same size and another two are longer and of the same size. These sides of equal length are parallel to each other.

This is how the rectangle consists of the union of these sides by four distinct points called vertices. Likewise, another fundamental feature of this geometric figure is that all the angles that make it up are of 90 degrees; that is, all its angles are right, and therefore, the internal sum of these angles will always result in 360 degrees.

As we usually proceed in a PROFESSOR, we leave you an image so that you can visually appreciate what is explained in this theoretical section about the shape of a rectangle and the angles it contains.

That said, and to achieve the objective of this lesson from a TEACHER, it is necessary to indicate that in geometry we call perimeter of a flat figure (since the perimeter can only be calculated if the figure in question only has two dimensions), to the length of its outline.

Therefore, perimeter is a measure of length and it is only reflected in linear units; for example: centimeters, meters, feet, inches, etc.

In other words, the perimeter of a figure in geometry is the sum of the sides that make up said figure. With this, we can calculate the total length covered by this flat figure if we add the size of all its sides.

Already presented the above, we have suggested how to get the perimeter of a rectangle. As we have mentioned in previous lines, the rectangle is made up of four sides, of which two are are shorter and equal to each other and the other two are larger and also equal to each other. Yes.

Consequently, the procedure for calculating the perimeter of a rectangle is very easy:

1. Add the length from its four sides
2. We will get the perimeter.

However, for theoretical purposes and to have a better structure when carrying it out, it is preferable to represent it with an example and a simple formula.

Suppose we have a rectangle whose sides have the following length: a = 5 centimeters; b = 12 centimeters.

Find the perimeter of the rectangle.

Solutions

Solution 1: Since we know that the perimeter of a rectangle is the sum of its four sides, we can proceed as follows.

• Perimeter = a + a + b + b
• Perimeter = 5 + 5 + 12 + 12
• Perimeter = 34 centimeters

Solution 2: Although the result will always be the same, the perimeter formula in the case of the rectangle can be represented in a more summarized way using the union of equal factors. It would be as follows:

• Perimeter = 2a + 2b
• Perimeter = (2 x 5) + (2 x 12)
• Perimeter = 34 centimeters.

If you want to read more articles similar to How to find the perimeter of a rectangle, we recommend that you enter our category of Geometry.