Excerpt from Numerical Problems in Descriptive Geometry: For Class and Drawing Room Practice 1. The distance of a point from the H plane is the distance of its V projection from the ground line. The distance of a point from the V plane is the distance of its H projection from the ground line. 2. If any two projections of a point are given, the point is fully determined, and the third projection may be found from the above principle. 3. If a line is parallel to either plane of projection, its projection upon the other plane of projection is parallel to the ground line. 4. If a line is parallel to either plane of projection, it will be projected upon that plane in its true length. 5. If two intersecting lines are each parallel to the same plane of projection, the angle between the lines will be projected upon that plane in its true magnitude. 6. If a point lies in a given line, its projections will lie in the corresponding projections of the line. 7. If two lines are parallel in space, their corresponding projections are parallel. 8. The H and V traces of a plane always intersect the ground line at the same point. 9. If any two traces of a plane are given, the plane is fully determined. 10. If a plane is parallel to the ground line, its traces are parallel to the ground line, and conversely. 11. If a plane is perpendicular to either plane of projection, its trace upon the other plane is perpendicular to the ground line, and conversely. 12. If a line lies in a given plane, its H piercing point lies in the H trace of the plane, and its V piercing point lies in the V trace of the plane. 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.