Plane Trigonometry: SL Loney's Original Classic

This is the most classic book on trigonometry available

Although this book dates back to 1893 it is still the definitive resource on trigonometry today. This book is required reading for aspiring mathematicians and physicists in India as they prepare for the IIT JEE exam. Not only is the text useful in conveying concepts, but the selection of problems is classic. This book is divided into two parts, geometric trigonometry and analytic trigonometry which is more formula based. This book has some advanced topics that can provide a transition into calculus. This book is a high quality reproduction of the original classic mathematics text from 1893. Although this book starts off with the basics, there is plenty of exciting advanced material presented: complex variables or infinite series for example. If you want to master the art of trigonometry this is one book you can't do without.

Learn like Ramanujan

The famous Indian mathematician Ramanujan is said to have mastered this book at a young age which contributed to his success. If you want to progress beyond the simplified way trigonometry is usually taught then you definitely will want to have this book.