Area and Perimeter
5.2 Area and Perimeter – Cheat Sheet
1. Rectangle
| Property | Formula | Notes |
|---|---|---|
| Perimeter | P = 2(l + w) | l = length, w = width |
| Area | A = l × w | Units: m², cm², etc. |
Example: l = 8 cm, w = 5 cm → P = 26 cm, A = 40 cm²
2. Triangle
| Property | Formula | Notes |
|---|---|---|
| Perimeter | P = sum of all sides | a + b + c |
| Area | A = ½ × base × height | Height ⟂ base |
Example: b = 10 cm, h = 6 cm → A = ½ × 10 × 6 = 30 cm²
3. Parallelogram
| Property | Formula | Notes |
|---|---|---|
| Perimeter | P = 2(a + b) | a, b = adjacent sides |
| Area | A = base × height | Height is perpendicular distance between parallel sides |
Example: b = 12 cm, h = 5 cm → A = 60 cm²
4. Trapezium
| Property | Formula | Notes |
|---|---|---|
| Perimeter | P = sum of all sides | a + b + c + d |
| Area | A = ½ × (sum of parallel sides) × height | Parallel sides = a, b |
Example: a = 8 cm, b = 5 cm, h = 4 cm → A = ½ × (8 + 5) × 4 = 26 cm²
5. Units
- Perimeter: same unit as lengths (m, cm, mm, km).
- Area: unit² (m², cm², mm², km²).
6. Quick Reference Table
| Shape | Perimeter Formula | Area Formula |
|---|---|---|
| Rectangle | 2(l + w) | l × w |
| Triangle | a + b + c | ½ × b × h |
| Parallelogram | 2(a + b) | b × h |
| Trapezium | a + b + c + d | ½ × (a + b) × h |