Learn About Perimeter of Squares and Rectangles Perimeter of squares and rectangles. So the perimeter is the distance around the outside of a closed figure. So to find the perimeter of a polygon, we add the lengths of all its sides, also mentioned, the unit length used such as inches, feet, meters, miles, etc. So the perimeter is the distance around the outside of a closed figure. And to find the perimeter, it’s the sum of all the lengths, of all its sides. Alright. So let’s take a look at this first figure. Figure one is a rectangle. So the opposite sides are equal in length. Now we know that the length of this rectangle is 10, so we know that the length is 10. We also know what the width is. We know that the width of this rectangle is 5. So the perimeter of this rectangle will be the sum of all the sides of this rectangle. So the perimeter or P is going to be the length + width + length + width. So in other words, we have the length + width + length + width or you could say (2 x length) + (2 x width), or another way you can write it is 2 x (length + width). So let’s go ahead and use 2 x (length + width). So the perimeter = 2 x (length + width). So the length of this is 10 feet, plus the width which we said was 5 feet. So if I add these, I get 15, so 2 x 15 feet which I get 30. So the perimeter of this rectangle is 30. So remember that the perimeter of a rectangle is 2 x (length + width). Alright. Let’s take a look at our second figure, figure 2. So this figure is a square so all sides are equal. Each sides of the square measures 9 centimeters. A square is a special form of a rectangle with length and width that are equal. So the length equals the width. So the perimeter of a square will be the sum of all its sides. So it’s the side + side + side + side, so it would be 4 x side. So in this case, our side is 9, S is 9. So if S = 9, then our perimeter of this square would be 4 x 9 which is 36 centimeters. So the perimeter of figure 2 is 36 centimeters. Remember that the perimeter of a square is 4 x S. Okay. Things to remember and to keep in mind is that the distance around a shape is called a perimeter. Now in other words, the perimeter is the distance around the outside of the closed figure. The perimeter is the sum of all the lengths of the sides of the polygon. Now, the perimeter of a rectangle with the length and width is 2 x (L x W). The perimeter of a square is 4 x S. Remember to name the unit of your length used to measure the shape.