A good Open Source book on Analytic Geometry?

There are a huge number of older classics freely available on the internet, such as (google "last name" and "title" together to find them):

Maxime Bocher, Plane Analytic Geometry (1915)

Maria M. Roberts and Julia T. Colpitts, Analytic Geometry (1918)

William F. Osgood and William C. Graustein, Plane and Solid Analytic Geometry (1922)

Lewis Parker Siceloff, George Wentworth, and David Eugene Smith, Analytic Geometry (1922)

The following School Mathematics Study Group texts from the 1960's may also be of use:

Analytic Geometry, Student Text, Part 1. Revised Edition

Analytic Geometry, Student Text, Part 3. Revised Edition

Since you seem especially interested in 3-dimensional analytic geometry, you'll also want to google (in google-books) for books with "solid analytic geometry" in their titles.

(added next day) This morning I looked through the books I have at home and came up with the following additional suggestions (definitely not all the relevant books that I have, as I have a large number of old math books):

N. J. Lennes and A. S. Merrill, Plane Analytic Geometry (1929)

Virgil Snyder and C. H. Sisam, Analytic Geometry of Space (1914)

V. A. Ilyin and E. G. Poznyak, Analytic Geometry (1984, MIR Publishers)

Joseph H. Kindle, Schaum's Outline of Theory and Problems of Plane and Solid Analytic Geometry (1950)

John M. H. Olmsted, Prelude to Calculus and Linear Algebra (1968)

William H. McCrea, Analytical Geometry of Three Dimensions (1960; Dover edition 2006)

Barry Spain, Analytical Conics (1957; Dover edition 2007)

Of all the books I've listed, my guess is that Kindle's book and Olmsted's book would be best for you. These two books should fit together well for self-study, since Kindle is more old-fashioned in style (with a huge number of problems) and Olmsted is more modern in style (with fewer problems, but much more careful text writing). ["Modern" means heavy use of set notation, functions as certain sets of ordered pairs, etc.]