What are Composite Figures?
Composite figures (or compound shapes) are shapes made up of two or more basic geometric shapes (rectangles, squares, triangles, trapeziums, etc.) combined together.
Strategy for Finding Area of Composite Figures:
| Step | Action |
|---|---|
| 1 | Divide the composite figure into simpler shapes |
| 2 | Calculate the area of each simple shape separately |
| 3 | Add areas for shapes that are combined |
| 4 | Subtract areas for holes/shapes that are cut out |
| 5 | Write final answer with correct units |
Strategy for Finding Perimeter of Composite Figures:
- Trace the outer boundary of the figure carefully
- Add the lengths of all outer sides
- Do NOT include internal lines where shapes join
Common Composite Figure Types:
| Type | Approach |
|---|---|
| L-shape (two rectangles) | Split into two rectangles, add areas |
| Rectangle with triangle on top | Area of rectangle + area of triangle |
| Circle cut out of rectangle | Area of rectangle - area of circle |
| Trapezium + triangle | Add both areas |
| Irregular polygon | Divide into triangles and rectangles |
Real-life Applications:
- Floor plans of L-shaped rooms
- Gardens with rectangular lawn and triangular flower bed
- Construction of houses and buildings
- Land area calculation for irregular plots
- Design of logos and emblems