## FANDOM

75 Pages

The set of projectively extended real numbers is a set containing the real numbers, as well as a new element $\infin$ which is at both ends of the number line. It corresponds to the real projective line because the vertical line going upwards (slope of $+\infin$)and the vertical line going downwards (slope of $-\infin$) both have the same gradient. It can be thus be constructed from the set of extended real numbers by identifying $+\infin$ and $-\infin$.