from geometric figures. The work is so arranged that either view may be presented independently. The solutions of the oblique spherical triangle by means of auxiliary quantities, characteristic of astronomy, are included as interesting mathematical problems and as preparation for astronomical work. PREFACE TO THE SECOND REVISED EDITION The second edition embodies such modifications, rearrangements, and additions as have been suggested by experience in the classroom. Due to numerous requests tables have been added. Simple three-place tables have been included. By their use the numerical work is reduced to a minimum, thus leaving the student free to give more attention to the principles involved in the solution of a triangle. Accordingly a few triangles, suitable for three-place table or slide rule computation, have been introduced at the beginning of the list of problems under the right triangle and also under the oblique triangle. In order to give a wider range to computational work fourplace tables as well as five-place tables have been included. G. N. B. MINNEAPOLIS, MINNESOTA, W. E. B. 20. Trigonometric functions introduced 21. Definitions of the trigonometric functions 22. Values of the trigonometric functions of 30°, 45°, and 60° 23. Values of the trigonometric functions of 120°, 135°, and 150° 26. A given value of a trigonometric function determines an VARIATIONS OF THE TRIGONOMETRIC FUNCTIONS REDUCTION OF FUNCTIONS OF n 90° ± α 39. Values of functions at 0°, 90°, 180°, 270°, and 360° 40 46. Functions of 90° + a in terms of functions of a 47. Functions of 90°. -a in terms of functions of a 57. Representation of the trigonometric functions by lines 58. Variations of the trigonometric functions as shown by line |