Geometry » Calculating area with enclosure method
The enclosure method follows the following algorithm:
| 1. | Enclose the figure with a rectangle. |
| 2. | Number the created triangles. |
| 3. | Calculate the area of these triangles |
| 4. | Calculate the area of the figure by subtracting the area of the triangles from the area of the rectangle. |
Example
On the left you can see the figure, we need to calculate the area of. On the right you see that figure enclosed by a rectangle.
| Area rectangle | = 3 × 5 = 15 |
| Area triangle 1 | = 3 × 2 : 2 = 3 |
| Area triangle 2 | = 1 × 3 : 2 = 1.5 |
| Area triangle 3 | = 3 × 2 : 2 = 3 |
Area figure = 15 – 3 – 1.5 – 3 = 7.5 grid squares.