What is Perimeter – Introduction

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A perimeter is a measurement used to quantify the length of a path around a two-dimensional object’s outer edge. Hence it infers to the length of the path that bounds an area. It is derived from the Greek words ‘peri’ (meaning surrounding) and ‘metron’ (measuring) and was used for the first time in the 15th century.

The perimeter of a polygon – a two-dimensional object with angles, refers to the entire length of the sides or edges. However we use the term circumference to describe the measurement around a circle, which is simply the perimeter of circle.

We measure the length of the sides of a small shape with straight line sides using a ruler. The perimeter is calculated by summing the lengths of the shape’s sides/edges. We can use a string of thread to create curved forms by placing it once along the shape’s boundaries. For example, the perimeter of triangle can be calculated with the help of it’s sides.

Measuring straight line sides using a ruler to find the  Perimeter
Measuring straight line sides using a ruler to find Perimeter

The perimeter of an item can be calculated in a variety of ways. Knowledge of how to calculate the perimeter can help you figure out how long a fence should be to encircle a yard or garden, or how much decorative border to buy to cover the upper margins of a room’s walls. In addition, knowledge of a wheel’s perimeter, or circumference, will tell you how far it will roll in one rotation.

Measuring a circle's perimeter
Measuring a circle’s perimeter

Facts of Perimeter and Area

Perimeter and area are interconnected. If the perimeters of different shapes are the same, the areas of their respective shapes need not be the same. Consider a rope of length 24 cm and create different 2D shapes as shown in the image below.

Creating shapes with a rope of 24 cm
Creating shapes with a rope of 24 cm
Even the shapes have the same perimeter; each shape will have a different area. The area of a shape increases with the increase in the number of sides, even though the perimeter is constant. The values of perimeter and area are shown in the table given below.

Perimeter and area of shapes based on the sides
Perimeter and area of shapes based on the sides

The circle has infinite sides. Thus, the circle has more area than the other shapes.

Know more about other concepts of Geometry on 2D Shapes, Herons Formula, Area of Triangle, Perimeter of Circle and Types of Triangle.