Britannica Educational Publishing 
Britannica Guide to Geometry [PDF ebook] 

More than a study of shapes and angles, geometry reflects an amalgamation of discoveries over time. This book not only provides readers with a comprehensive understanding of geometric shapes, axioms, and formulas, it presents the field’s brilliant minds-from Euclid to Wendelin Werner and many in between-whose works reflect a progression of mathematical thought throughout the centuries and have helped produce the various branches of geometry as they are known today. Detailed diagrams illustrate various concepts and help make geometry accessible to all.