Measure of a two-dimensional closed surface.
- Synonym for surface area.
- The term surface area is generally used in the case of large surfaces.
- Area is a quantity that is almost always expressed using denominate numbers.
Examples
- The side c of a square measures 10 cm.
The area A of this square is 100 cm², because: A = c × c = 10 × 10 = 100.
- A rectangle measures 8 cm long (a) and 6 cm wide (b).
The area A of this rectangle is 48 cm², because: A = a × b = 8 × 6 = 48.
- The radius r of a circle measures 10 cm.
The area A of this circle is 100π cm², because: A = πr² = π × 10² = 100π.
Notation
The basic unit of area in the International System of Units (SI) is the square metre, noted as m².
The relationship among the different units of area are:
| km² | hm² | dam² | m² | dm² | cm² | mm² |
| 0.000 001 | 0.0001 | 0.01 | 1 | 100 | 10 000 | 1 000 000 |
Educational Note
The area of a figure is a measurement, so we should say the area of a square or the area of the surface of a square.