# Area

quantity that expresses the extent of a two-dimensional surface or shape, or planar lamina, in the plane

Area is the amount of space a two dimensional (flat) surface takes up. It is useful because it is how much of a material is needed to make a hollow container; for example, how much wood is needed to make a wardrobe.

You can use different formulas to find the area of different shapes.

• Area of a rectangle is the length of any two touching sides multiplied together. In other words, length times width.
• Area of a triangle is half of the base multiplied by the perpendicular height. This can be found using the trigonometry formula, ${\displaystyle A=1/2ab\sin c.}$.
• Area of a circle: ${\displaystyle A=\pi r^{2}}$.

The area of a flat object is related to the surface area and volume of a three-dimensional object.

The area under a curve can be found using integration, from calculus.

Some units used to measure area are square mile and square kilometre.