# Determining Exact Values

• April 21st 2012, 07:59 PM
Determining Exact Values
Hello. :) Would like some help please. :p

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)??? :/
• April 21st 2012, 08:02 PM
Prove It
Re: Determining Exact Values
Quote:

Originally Posted by ShootMePlease
Hello. :) Would like some help please. :p

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.
• April 28th 2012, 03:51 PM