103 Trigonometry Problems contains carefully selected problems and solutions used in the training and testing of the USA International Mathematical Olympiad (IMO) team. Though many problems may initially appear impenetrable to the novice, most can be solved using only elementary high school mathematics techniques. The key features of this book are Gradual progression in problem difficulty builds and strengthens mathematical skills and techniques. Basic topics include trigonometric formulas and identities, their applications in the geometry of the triangle, trigonometric equations and inequalities and substitutions involving trigonometric functions. Problem-solving tactics and strategies, along with practical test taking techniques, provide in-depth enrichment and preparation for possible participation in various mathematical competitions. Comprehensive introduction (first chapter) to trigonometric functions, their relations and functional properties and their applications in the Euclidean plane and solid geometry expose advanced students to college level material.