Book excerpt: Excerpt from Notes on Elements of (Analytical) Solid Geometry The projection of a line on a plane is the line containing the projections of its points on the plane. When one line or several lines connected together enclose a plane area, the area enclosed by the projection of the lines is called the projection of the first area. The idea of projection may be in the case of the straight line thus extended: if from the extremities of any limited straight line we draw perpendiculars to a second line, the portion of the latter intercepted between the feet of the perpendiculars is called the projection of the limited line on the second line. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.