what is the basic way to study this topic??i mean trigonometery......it's kinda difficult
Frankly, there is a lot of memory in Trig.
Flashcards are helpful.
Practice problems are helpful.
I also strongly recommend Schaum's Outline Series, Trigonometry, available at most bookstores, it is really good, and inexpensive. Visit a local BarnesNoble, and take a look.