Note 121 — Chapter III
Reading edition
The straight line σa denotes the straight line common to the planes σ and a, the point σa denotes the point common to the plane σ and the straight line a, and similarly for the rest of the notation.
Reading edition
The straight line σa denotes the straight line common to the planes σ and a, the point σa denotes the point common to the plane σ and the straight line a, and similarly for the rest of the notation.