Important area formulas of 2D shapes
| 2D shape | Area |
|---|---|
| Rectangle | l × b |
| Square | a × a = a2 |
| Parallelogram | b × h |
| Rhombus |
b × h
or 12 × d1 × d2 |
| Trapezium | 12(a + b) × h |
| Triangle | 12 × b × h |
| Isosceles triangle | b √a² – b² 4 |
| Equilateral triangle | √3 4 a² |
| Circle | πr2 |
Perimeter formulas of 2D shapes
| 2D shape | Perimeter |
|---|---|
| Rectangle | 2(l + b) |
| Square | 4a |
| Parallelogram | 2(a + b) |
| Rhombus |
4a
or 2 √d1² + d2² |
| Trapezium | a + b + c + d |
| Triangle | a + b + c |
| Isosceles triangle | 2a + b |
| Equilateral triangle | 3a |
| Circle | Circumference = 2πr |
