The ???Classic Text Series??? is the only of its kind selection of classic pieces of work that started off as bestseller and continues to be the bestseller even today. These classic texts have been designed so as to work as elementary textbooks which play a crucial role in building the concepts from scratch as in-depth knowledge of concepts is necessary for students preparing for various entrance examinations. The present book on Plane Trigonometry Part 1emphasis on presenting the modern treatment of various concepts of Plane Trigonometry. The book has been divided into 21 chapters namely Measurement of angles; Sexagesimal and Centesimal Measure Circular or Radian, Measure, Trigonometrical ratios for angles less than a right angle, Simple problems in Heights & Distances, Applications of algebraic signs to Trigonometry tracing the changes in the ratios, Trigonometrical ratios of angles of any size & sign, General expressions for all angles having an given trigonometrical ratio, Trigonometrical ratios of the sum & difference of two angles product formulae, Trigonometrical ratios of multiple & submultiple of angles, Identities &trigonometrical equations, Logarithms, Tables of Logarithms, The Principle of Proportional parts, Relations between the Side &Trigonometrical ratios of the Angles of a triangle, Solution of triangles, given two sides & the included angle, ambiguous case, Heights & Distances, Properties of a triangle, Quadrilaterlas, Regular Polygons, Inverse circular functions, Summation of some simple trigonometrical series, Elimination and Projections,each covering various concepts of Plane Trigonometry. Theoretical explanation of the concepts in points has been provided at the beginning of each chapter. At the end of each chapter, unsolved practice exercises have been provided to help aspirants revise the concepts discussed in the chapter. At the end of chapterwise study, miscellaneous examples have also been given. Also five-figure logarithmic and Trigonometrical Tables have been covered at the end of the book. As the book covers all the aspects of Plane Trigonometry, it for sure will serve as the complete elementary textbook for studying various elements of Plane Trigonometry (Part 1).