Two of the most recommended books for the students who are preparing for upcoming JEE exams are Plane Trigonometry Part I (S L Loney) and The Elements of COORDINATE GEOMETRY Part-1 Cartesian Coordinates.
Plane Trigonometry Part I (S L Loney)
The book is one of the classic books ever written on trigonometry.
One thing I found about the book was its theoretical way to describe things. This book starts explaining the trigonometry from the zero level, starting from measuring the angles. A very good thing about the book is that the concepts are explained clearly. Jee aspirants should read this book to have a good grasp on trigonometry which is useful in other topics like the co-ordinate geometry and calculus.
The book really works well with its another part which is The Elements of COORDINATE GEOMETRY Part-1 Cartesian Coordinates. The other book is also a very standard book to follow for JEE aspirants.