Textbook in PDF format

A course of trigonometry.
Trigonometry is an ocean, and you can find it everywhere. It explains many, if not all, phenomena. The book provides uncomplicated logical intuitions and proofs to explain related mathematical findings. Numerous examples are presented to better facilitate the learning and understanding process.
My intention in writing this book is to introduce ways that we can apply mathematics, or, specifically, trigonometry, in the simplest way possible to understand while providing numerous examples.
A course of trigonometry can be surprisingly confusing and somewhat counter-mathematical, an increasing number of identities that seem to be unending sometimes, question is how can I understand these formulas intuitively? The way a mathematician does, not based on artificial definitions and symbols, but rather getting into the heart, the essence of the subject, a way of thinking that can make them trivial, give the feeling of why they work, aside from the way we prove them.
Preface
Introduction
Simple Approach to Trigonometric Nuts and Bolts
Right Triangles
Trigonometric Identities
Sine and Cosine Laws
Graphing Trigonometric Functions
Inverse Trigonometric Functions
Index