Trig Identity Reference

Are you referring to the Trig identity reference article of the Precalculus course? Please include a link in the future.

Frankly, in the Calculus courses I just used the identities without understanding them. You only need to genuinely understand sine, cosine and tangent.

I must say I don’t find the diagrams in the Trig identity reference article particularly helpful either, but maybe there is at least one learner out there who does appreciate them.

If you provide the title of the course and the unit/lesson/title of the explanations, maybe the rest of us can look at it and understand what you're referring to.

Sorry.

Precalculus, Unit 2, Lesson 10, 

Trig identity reference

Reciprocal and quotient identities, 

I have a very hard time learning anything without understanding how and why it works.