pi (π)=3.1415926535 ...
| Shape | Formula | |
|---|---|---|
| ◯ | Circle | pi × radius2 |
| ◻ | Square | side2 |
| ⌷ | Rectangle | length × width |
| ▱ | Parallelogram | base × height |
| △ | Triangle | base × height / 2 |
| ⬠ | Regular n-polygon | (1/4) × n × side2 × cot(pi/n) |
| ⏢ | Trapezoid | height × (base1 + base2) / 2 |
| ⬭ | Ellipse | pi × radius1 × radius2 |
Source: Spiegel, Murray R. Mathematical Handbook of Formulas and Tables.
Schaum's Outline series in Mathematics. McGraw-Hill Book Co., 1968.