I would recommend Trigonometry, 3rd Edition by Cynthia Young, ISBN-13: 978-0470648025 and the Student Solution Manual by Mark McKibben, ISBN-13: 978-1118101148
The explanations are very clear and the material builds on itself in a logical progressive way.
She teaches you in a way that a teacher in a classroom would explain how to solve a problem step by step by stating in a sentence what is to be done mathematically and then on the same line presents the mathematical equivalent so that you understand each step in the solution process until the answer is obtained.
The most important information is summarized at the end of every module for quick reference. And, general concepts are summarized on the front and back inside cover of the textbook.
Learning math involves practice and she provides many problems for each short segment of material. Problems progress from simple to more difficult in the problem set.
She includes a couple of problems with each problem set called "Catch the Mistake" which are common mistakes that students often make.
Answers to most of the odd problems are given in the back of the book, but I would also recommend purchasing the Student Solution Manual (which provides answers to all of the odd problems) since it is not always obvious (to me at least) how the solution was obtained for some of the more difficult problems.
She also has many short illustrations in the margin of the textbook of how to use a Texas Instruments calculator which can be very helpful to those not familiar with the graphing calculator.
There are also other very good Trigonometry only textbooks, but this is a good one to start with and a motivated individual can teach himself/herself Trigonometry without an instructor by diligently studying this textbook.
There are two appendices including a section on basic algebraic concepts and another on conic sections.
No math book is perfect and students with different personalities or learning preferences may prefer other textbooks and that is fine. Nevertheless, if one learns the material in this textbook, he/she has learned a lot of Trigonometry.
Please note that this book devotes itself to Trigonometry, however, and you may prefer a book that combines Algebra with Trigonometry or a Precalculus mathematics textbook which includes other material along with Trigonometry.
Even if you may be using another textbook, this book would be very useful for explaining concepts that may not be fully explained in the other textbook.
Before using this textbook, one should be able to perform basic mathematical and algebraic manipulations so that this is not a stumbling block to learning Trigonometry.
The textbook has a considerable number of pages, but one need not work every problem nor cover all of the subjects in the textbook.
While some of the material is needed to understand concepts later on in the book (especially at first), this is not always the case, so you shouldn't rule out this textbook just because of the number of pages in it.
Basic concepts are explained very well and this is tremendously valuable to the reader even if one skips sections of it.
If you buy both the textbook and the student solution manual the books are not cheap, but there are probably many cheaper yet good quality used copies of these same books available online.
I hope that this helps!