Formula Table
| Shape | Area | Perimeter / circumference |
|---|---|---|
| Square | s² | 4s |
| Rectangle | l × w | 2(l + w) |
| Triangle | ½bh | a + b + c |
| Parallelogram | bh | 2(a + b) |
| Trapezium | ½(a + b)h | sum of all sides |
| Circle | πr² | 2πr or πd |
| Ellipse | πab | No simple elementary exact formula |
Symbols
s = side, l = length, w = width, b = base, h = perpendicular height, r = radius, d = diameter, and π ≈ 3.14159.
Worked Examples
Rectangle 6 m × 4 m: area = 24 m²; perimeter = 20 m.
Circle radius 3 m: area ≈ 28.27 m²; circumference ≈ 18.85 m.