Trigonometry

I'm doing pretty well in my trig but I seem to have hit a roadblock in establishing this particular identity. Here's what I have so far:

(tan(2pi)-tan(theta)) / (1+tan(2pi)tan(theta)) = -tan(theta)

If someone would be so kind as to tell me what my next step should be I would be grateful(I'm only working on the left side of the identity.) I only need the next step, I'm pretty sure I'll understand after that.

What identity?

>>2
I need to establish that the equation I posted above is true.
Using these identites:

http://en.wikipedia.org/wiki/List_of_trigonometric_identities#Angle_sum_and_difference_identities

Only the Sine, Cosine and Tangent identities need to be used.
Sorry if my wording confused you, it's how my book words things.

uh, tan(2pi) = 0, perhaps?

(tan(2pi)-tan(theta)) / (1+tan(2pi)tan(theta)) = -tan(theta)
-tan(theta) / tan(theta) = -tan(theta)
tan(theta) = 1
theta = pi/4

Fuck using any identity

tan(2pi) = 0

(0 - tan(theta) / (1 + 0 * tan(theta) =
-tan(theta) / 1 =
-tan(theta)

But if you have to use the addition and subtraction formula, then your equation becomes:

tan(2pi - theta)

since 2pi is coterminal to 0pi

tan(0pi - theta)
tan(-theta)
sin(-theta)/cos(-theta)

since

sin(-theta) = -sin(theta)

and

cos(-theta) = cos(theta),

then

-sin(theta)/cos(theta) =

-tan(theta)