Excerpt from Plane and Spherical Trigonometry This book originated in a desire to give to my private pupils a better idea of the trigonometric functions of obtuse angles than they could obtain from any book with which I was acquainted, I believe that a student can get a comprehensive and thorough knowledge Of trigonometry most quickly and easily, if, at the outset, such definitions are given to the trigonometric functions as will apply to all angles with this idea for a basis, I have endeavored to prepare an elementary text-book for general use. By beginning with an explanation of the use of the negative sign as applied to lines and angles, and then giving general definitions to the trigonometric functions, I have been able to demon strate all the fundamental formulas in a perfectly general yet simple manner. 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.