Question

is there any need for understanding the concept of trigonometric ratios or simply study it

Answer 1

You need to understand the trigonometric concepts because it has many identities and formulae. If you would simply read it, you may find problems in solving questions in the examination hall. First and second part of the trigonometric chapter are easy the part of identities is a little bit tough. So, you should try to clearly understand it.
THANK YOU.

Answer 2

you just need to understand how you get the values for sin and cos. you can derive the others from them.
these are the basics for formulas and all