Two-dimensional shapes are flat. The perimeter of a 2D shape is the total distance around the outside of the shape. The area of a 2D shape is the space inside the shape. Compound shapes can be split into different squares, rectangles and triangles to work out total area.

Part of

To calculate the area of a triangle, draw a second triangle to form a rectangle.

The area of the rectangle is 8 cm^{2}.

Two triangles make the rectangle. The area of one triangle is half the area of the rectangle.

\[8 \div 2 = 4~\text{cm}^2\]

The area of a triangle can also be calculated using the formula:

\[\text{area of a triangle} = \frac{1}{2} \text{base} \times \text{height}\]

or

\[\text{area of a triangle} = \frac{\text{base} \times \text{height}}{2}\]

In this case:

\[\frac{2 \times 4}{2} = 4~\text{cm}^2\]