Use Sin,Cos, and Tan to solve. Sometimes you will have to use Sec, Csc, and Cot  to solve these problems as well. The unit circle may seem daunting and incomprehensible at first but if you study it hard and use this website effectively then you will master the unit circle in no time. Here is a brief description of what each page of the website offers
How to use the unit circle- it will describe study tips and how to fill it out
History of the unit circle-will describe what its used for
Easy problems- this will be the easiest problems you will find on the unit circle
Medium- its advised that you have memorized the circle at this point
Hard- don't try these unless you have mastered the easy and medium
Real World-these problems are the kind that would be in a math book
Answers-the answers to the third problem of every set
Bibliography/ Other websites- these websites could offer extra help