
Trig Identities
I am not understanding at all how to do the trigonometric identities...
As far as i know we had 12 of them that we had to memorize, even after memorizing them i am unsure of how to apply them.
so for my first question the problem says
(sinx + cosx)(sinx + cosx) 1 / sinxcosx
multiply and simplify
the answer is 2 however im unsure how you get that answer.
also there is
1 + tan^2(x) = sec^2(x)
how do I get both sides to equal the same im suppose to use the more complicated side, but, which identity do I use?
If there is any easy way to remember the identities and to apply them that would be great..
thanks in advance

$\displaystyle \frac{(\sin{x}+\cos{x})^2  1}{\sin{x}\cos{x}} =
$
$\displaystyle \frac{\sin^2{x} + 2\sin{x}\cos{x} + \cos^2{x}  1}{\sin{x}\cos{x}} $
now ... what do you know about the sum $\displaystyle \sin^2{x} + \cos^2{x}$ ?
$\displaystyle 1 + \tan^2(x) = \sec^2(x)$
note that $\displaystyle \tan^2(x) = [\tan(x)]^2$ and that $\displaystyle \tan(x) = \tan(x)$

sin^2x+cos^2x = 1, so
1 + 2 1 = 2 oo.....
ok and then
1 + tan x^2
1 + tan x^2 = sec x^2
oo.... thanks
ok I understand it when someone tells me what to do, but i cant think of what to use when i have to do it all alone :S
so i have 2 more problems
tanx + cosx /1+sinx = secx
so er...
sinx/cosx + cosx/1+sinx = secx
is that correct? where do i go after that? :/
also
sinx/sinx  cosx = 1 /1  cotx
is there any way of really knowing what you have to use? still confused alot thank you
