## Area

Area is the amount of space taken up by a surface. The areas and perimeters of simple figures such as squares and rectangles can be calculated using formulae. The perimeter of a shape is the total length of all of its sides.

Units of Area

Perimeters are measured using the units of length, i.e. metres.

There are two basic units for measuring area:

• A square metre is the area occupied by a square with each side 1 metre long. It is written as 1 m2.
• An are is the area occupied by a square of length 10 m.

Other common units for area are:

 Unit Symbol Units for measuring: Conversion Square centimetre cm2 Paper, material 10 000 cm2 = 1 m2 Square kilometres km2 Area of countries 1 km2= 106 m2 Hectare ha Land area, e.g. farms 1 ha= 10 000 m2

### Area and Perimeter Formulae

 Shape Name Perimeter Area Square P= 4 × l = 4l A = length × width = l2 Rectangle P = 2b + 2h A = base x height = b × h = bh Triangle P = a + b + c A= half × base × height  Parallelogram P = 2b + 2a A = base × height = bh Rhombus P = Sum of all sides = 4b  Trapezium P = Sum of all sides  Circle Perimeter is called thecircumference C = 2 r = d A = r2 is a special number approx. 3.1416 (to 4 d.p.) or or 