## Methods for Finding Area

## Formative Assessment

# Summary of the Math: Methods for Finding Area

**Read and Discuss**

- Knowing the formulas for the area of a triangle and the area of a rectangle allows you to determine the area of all other polygons, regular and irregular.
- For parallelograms and trapezoids, you can find the area by decomposing the polygon into combinations of right triangles and rectangles and then adding the areas of the component shapes.
- For other polygons, a good method to use is to first construct any one diagonal of the polygon. Then join each of the other vertices to the diagonal with perpendicular line segments. Decompose any trapezoids that are formed in this process into rectangles and right triangles and then find the areas of the component shapes.
- You can also draw a familiar figure around the composite figure and use subtraction to find the area of the composite figure.

## Hint:

Can you:

- Find the areas of composite figures?
- Give examples to illustrate your strategies for finding the areas of composite figures?