# Math Help - Determining Exact Values

1. ## Determining Exact Values

Hello. Would like some help please.

Okay, so:

tan(7Pi/4)
= -tan(Pi/4)
= -1

I understand how it's -tan, and how it equals -1, but how/why did the brackets change from (7Pi/4) to (Pi/4)??? :/

2. ## Re: Determining Exact Values

Hello. Would like some help please.

Okay, so:

tan(7Pi/4)
= -tan(Pi/4)
= -1

I understand how it's -tan, and how it equals -1, but how/why did the brackets change from (7Pi/4) to (Pi/4)??? :/
Because \displaystyle \begin{align*} \frac{7\pi}{4} = 2\pi - \frac{\pi}{4} \end{align*}, which is in the fourth quadrant.

So it's basically asking you to evaluate \displaystyle \begin{align*} \tan{\frac{\pi}{4}} \end{align*}, but to then take into account the fact that the tangent function is negative in the fourth quadrant.

3. ## Re: Determining Exact Values

Thank you! That makes much more sense now.