Perimeter

The perimeter of a polygon is the distance around the outside of the polygon. A polygon is 2-dimensional; however, perimeter is 1-dimensional and is measured in linear units. Perimeter is the total distance around any polygon (any 2D figure). Perimeter can be calculated by adding the length of the sides. Examples: The perimeter can be used to calculate the length of fence required to surround a yard or garden. The perimeter of a wheel (its circumference) describes how far it will roll in one revolution. Similarly, the amount of string wound around a spool is related to the spool's perimeter.

Perimeter of any figure = Sum of all the sides of the figure

We shall see the very basic word problems in perimeter in this section:

1. Find the perimeter of a rectangle whose length is 8cm and width is 3cm.

Solution:
The perimeter of rectangle can be calculated as the sum of all the sides, which is
L + L + W + W = 2L + 2W
Where L = length and W = width
Here L = 8cm and W = 3cm
Perimeter = 2L + 2W
= (2x8) + (2x 3)
= 16 + 6
= 22cm

2. Find the perimeter of triangle whose sides are given by 3cm , 4cm and 5cm.

Solution:
Sum of all the sides gives the perimeter, here the three sides are 3 , 4 and 5
So perimeter = 3 + 4 + 5
= 12cm

3. Find the perimeter of the circle with radius 5cm

Solution:
Perimeter of circle is nothing but the circumference of the circle.
Circumference of the circle = 2 π r
Here r = radius = 5 cm
Circumference = 2π ( 5) = 10 π cm
π = 3.14
So circumference = 10 x 3.14 = 31.4cm