# 1.2 Calculations are carried out correctly and the least steps of instruments used are taken into account when reporting final values.

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*Length and breadth:*

Length is always the longer side of a shape, while breadth is the shorter side. In the examples below, the double lines indicate the length while the single lines indicate the breadth. Length and breath are indicated in metres. Any shape that has length and breadth is a two-dimensional shape**. **

*Perimeter and circumference:*

Perimeter is the distance from one point on the outside border of a shape, all the way around, to the same point again. Perimeter and circumference are measured in metres.

To calculate the perimeter of a rectangle, square or parallelogram:

P= 2 lengths + 2 Breadths

And the answer is in mm,cm,m or km.

Example:

To calculate the perimeter of the figure below:

P = 2l + 2b

= 2(10) + 2(2)

= 20 + 4

= 24cm

To calculate the perimeter of any straight-lined shape with more than four angles: P = total sum of the length of all the straight lines.

*Circumference*

Circumference is similar to perimeter, but circumference is the word we use to describe the ’perimeter’ of a circular shape.

To calculate the circumference of a circle:

Where p is 22 or 3,14

7

Example:

To calculate the circumference of the circle below, where p = 3,14:

= 2(3,14)(5 ¸2)

= 2(3,14)(2,5)

= 15,7 cm

** **

*Area and volume*

Area is the amount of space a shape takes up in two dimensions, i.e. length and breadth.

Volume is the space that a container can take on the inside. In order to determine the volume of a container, we need to add another dimension to the shape namely the height or depth**.**