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
Area and Perimeter Formulae
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 countriesY10_Area_01.gif

1 km2= 10m2

Hectare
ha
Land area, e.g. farms

1 ha= 10 000 m2 

Area_Formula.jpgArea and Perimeter Formulae

Shape
Name
Perimeter
Area
Y10_Area_02.gif
Square

P= 4 × = 4l

A = length × width

l2

Y10_Area_03.gif
Rectangle

P = 2b + 2h

A = base x height

b × h

bh

Y10_Area_04.gif
Triangle

P = a + b + c

A= half × base × height

Y10_Area_05.gif

Y10_Area_06.gif

Parallelogram

P = 2b + 2a

A = base × height

bh

Y10_Area_07.gif

Rhombus

P = Sum of all sides = 4b

Y10_Area_08.gif

Y10_Area_09.gif

Trapezium

P = Sum of all sides

Y10_Area_10.gif

 

Y10_Area_11.gif
Circle

Perimeter is called thecircumference

C = 2Y10_Area_12.gifr

Y10_Area_12.gifd

A = r2

 is a special number approx. 3.1416 (to 4 d.p.)

or Y10_Area_13.gif or Y10_Area_14.gif