# Coxeter- Exercise 5.2.1

- Author:
- AndrewLyon

- Topic:
- Geometry

Exercise 5.2.1 What happens to the parabolic projectivity

*ACC*projective to*A1CC*when*PQ*is the line at infinity? As opposed to the figure associated with theorem 5.21, the figure displayed here is constructed so that*P*can be adjusted and brought to be horizontal with point*Q*projecting the intersection of the line*QP*and*AC*to infinity.