Perimeter Formulas
Perimeter is the total length of a shape’s boundary, measured in ordinary length units.
Formulas
| Shape | Perimeter |
|---|---|
| Square | 4s |
| Rectangle | 2(l + w) |
| Triangle | a + b + c |
| Circle | 2πr = πd |
| Semicircle | πr + 2r |
| Sector | 2r + (θ/360) × 2πr |
| Regular polygon | n × s |
| Parallelogram | 2(a + b) |
| Ellipse (approx.) | π[3(a + b) − √((3a + b)(a + 3b))] |
Example
A running track: two straights of 84.39 m, two semicircles of radius 36.8 m
- Straights: 2 × 84.39 = 168.78
- Curves: 2πr = 2π × 36.8 ≈ 231.22
≈ 400 m (measured on the inside lane).