Length: perimeter and circumference

Perimeter is the total length of all sides of a figure or shape. It is measured in metres(m) or centimetres (cm)

Perimeter of irregular shapes

Example

Perimeter= total number of all the number in the diagram 

Perimeter= 3+3+3+3+3+3cm

                   = 18cm 

 Perimeter of regular shapes

Regular shapes are rectangle and square

Formular for perimeter of regular shapes 

Perimeter = 2(L+ B) cm or m

Example 1

Length = 6.5cm 

Breadth = 3.5cm

Solution 

Perimeter= 2(L+B)cm

                  = 2 ( 6.5  + 3.5) cm

                  = 2 (10.0) cm

                 = 20.0cm

Lesson 2

Circumference of a circle

Circumference of a circle = πd or 2πr

Note: π = 3.14

Example 

If a diameter of a circle is 5cm, find the circumference (π=3.14)

Solution 

Diameter = 5cm and π= 3.14

C = πd

C= 3.14x 5cm

C= 15.70cm

Activities 

MacMillan Champion Mathematics Bk 5