Understanding Trig Identities: Sum and Diff. & Multiple Angle

[tanisha89]

can anyone help me understand the following and how to apply them:

tig identities
sum and diff. indentities
multiple angle indentities

I'd really appreciate it. Thanx

 

[symbolipoint]

For understanding, some rely on equation for a circle; for many, graphical representations help to derive and then apply in theoretical exercises.

For practical applications, look to physics and engineering. Law of Cosines and law of Sines are often applicable. One of the Trigonometry books by Larson (and who else?) have some exercises for vectors that occur in physics.

 

[clustro]

it really only gets better by doing lots of problems that require them.

But really, if you're trying to solve something that involves trig, and the result is too ugly or irreducible, I would consult the wikipedia trig identity list.

 

[MagikRevolver]

I don't think anyone is going to be able to directly help or teach you trig through a forum. If you have a teacher, ask him/her. That's what I found worked, and like said before practice the problems. Have the idents next to you as you practice a variety of problems, evuntually you will learn and memorize them.