It will be assumed that you are familiar with the results from Euclidean and coordinate geometry listed below.

(C.110) |

(C.111) |

(C.112) |

We will always assume that angles are measured in radians unless otherwise specified. If an angle is inscribed in a circle of radius and is the length of the subtended arc, then

A right angle is and the sum of the angles of a triangle is . When is four right angles in (C.113) we get

(C.114) |

(C.115) |

In particular when is four right angles

(C.116) |