pi (π)=3.1415926535 ...

Shape | Formula | |
---|---|---|

◯ | Circle | P= 2 × pi × radius |

◻ | Square | P= 4 × side |

⌷ | Rectangle | P= 2 × (length + width) |

▱ | Parallelogram | P = 2 × (side1 + side2) |

△ | Triangle | P= side1 + side2 + side3 |

⬠ | Regular n-polygon | P= n × side |

⏢ | Trapezoid | P= base1 + base2 + side1 +side2 |

⬭ | Ellipse | 4 × radius1 × E(k,pi/2) E(k,pi/2) is the complete elliptic integral of the second kind k = (1/radius1) × sqrt(radius1 ^{2} - radius2^{2}) |

Source: Spiegel, Murray R. Mathematical Handbook of Formulas and Tables.

Schaum's Outline series in Mathematics. McGraw-Hill Book Co., 1968.