determine the quadrant in which an angle lies. help!

Mar 2012
124
1
nyc
hello u math brainiacs (Cool) i need help!

how do i go about determining which quadrant the angle lies in?

ex) -5pi/6 please explain thoroughly so i can take notes and as easy as possible :) because i tried and cant figure it out.

thanks!
 

Plato

MHF Helper
Aug 2006
22,492
8,653
how do i go about determining which quadrant the angle lies in? ex) -5pi/6
\(\displaystyle \frac{-5\pi}{6}\) is equivalent to \(\displaystyle \frac{-5\pi}{6}+2\pi=\frac{7 pi}{6}\).
\(\displaystyle \frac{7 pi}{6}\in III\) WHY?
 
Mar 2012
124
1
nyc
so thats it? just find the equivalent and then locate that equivalentbon on the unit circle?
 
Mar 2012
124
1
nyc
and what about -11pi/9 i got the answer as 7pi/9 cant locate that on the unit circle...
 

Plato

MHF Helper
Aug 2006
22,492
8,653
and what about -11pi/9 i got the answer as 7pi/9 cant locate that on the unit circle...
Well \(\displaystyle \frac{1}{2}<\frac{7}{9}<1\) so it is in II.
 
Mar 2012
124
1
nyc
i understand what ur saying.

what about when im given something like just 3.5?
 

Plato

MHF Helper
Aug 2006
22,492
8,653
i understand what ur saying.
what about when im given something like just 3.5?
If \(\displaystyle \pi<3.5<\frac{3\pi}{2}\) in it is in III.
 
Mar 2012
124
1
nyc
yes, ofcourse. y didnt i see that? thank you very very much!