Excerpt from Plane Trigometry While the importance of the function concept for elementary mathematics has become recognized by many writers of college algebra texts and of unified freshman mathematics books, it has received little recognition from writers on elementary trigometry. To emphasize this importance has been the leading motive in writing the present book. A somewhat detailed study of the graphs of the trigometric functions (Chapter V) and of the inverse functions (Chapter VIII) has been introduced for this purpose. Much more could and should be done in this direction; perhaps the present effort may suffice as a first step. The opportunity afforded by the writing of a new text has been used to make some changes in the presentation of the traditional material. Circular measurement of angles is introduced in the first chapter so as to be available for use throughout the course. The fundamental theorems on projections are presented early and are used subsequently so that the student may be familiar with them when they are applied in a general proof of the addition theorems, based on a method quite generally followed by continental writers. Recognizing the value of the solution of triangles, a good deal of space has been devoted to this subject, and an attempt has been made to develop it in such a manner that the student can appreciate the reasons for the different methods that are discussed. On the question of applied problems, I have taken a definite position. I do t think it feasible to introduce into an elementary text technical material from the applied sciences, important though such material may be. Without such material, however, applications cant well be anything but problems which use the language of the applied sciences without really belonging to them. 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 techlogy 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.