PERIMETER OF PLANE SHAPES

PERIMETER OF PLANE SHAPES 

Definitionn of perimeter

  Perimeter is the sum of the length of all the edges of a plane shape. The perimeter of regular and irregular shapes can be found by adding up all the length of the sides present in the given shape.

 Perimeter of irregular shapes

The perimeter of irregular shape can be found by adding up all the length of the sides of the irregular shape. For example, Consider the irregular shapes shown below,

the perimeter of The shape is the sum of all the lengths of of each of the sides of the shape. That is,the perimeter of the irregular shape = b + d + a + c. 

Examplee 1: Calculate the perimeter of the irregular shape shown below:

Solution 1: The perimeter of the irregular shape = Sum of all the length of each side of the shape.

Perimeter of the irregular shape = AB + BC + CD + DE

Perimeter of irregular shape = (2.8 + 2 + 2.5 + 1.8 + 2.5) cm

= 11 cm

Note: There is no fixed formula for solving the perimeter of irregular plane shapes. Their perimeter is calculated by simply adding up the length of their sides.

Perimeter of Regular plane shapes

Examples of regular plane shapes are circles, Triangles, quadrilaterals and the polygons. We can calculate the perimeter of plane shapes by using the basic principle used for finding perimeter of plane shapes. However, formula can be used to carry out the same task. In the subsequent paragraphs we shall be deriving the formula for calculating different regular plane shapes.

Perimeter of a square

Given a square ABCD whose length is l as shown below

Since AD = l and AB = BC = CD = l (All sides of a square are equal)

Hence, the perimeter of the square = l + L + l + l = 4l

The perimeter of a square= 4l

Example: 

 For the regular plane shapes, we derive formula for solving their perimeter. This is done in the subsequent paragraphs.

Perimeter of square