# Referencce Angle

• Oct 25th 2006, 03:48 PM
qbkr21
Referencce Angle
I was wondering what the reference angle is for:

theta=3 (no degrees, so I am assuming it is in radians)

Here is what I did:

LIke I said I am assuming that the 3 is in radians

If I'm not mistaken a reference angle is how far away an angle is from the nearest X-axis so with that being said here is how I went about buisness:

180*3=540 degrees

90+90+90+90+90+90=540 degrees

On the first revolution of the unit circle it would land on the 180 degree mark

Now as you can see this angle lands directly on top of the 540 because it is 540

540=540

I have tried various answers such as 0,-1, pi, -pi and the computer system still won't bite. Any suggetions?
• Oct 25th 2006, 04:27 PM
topsquark
Quote:

Originally Posted by qbkr21
180*3=540 degrees

Your formula isn't correct. $\displaystyle \pi$ rad = 180 degrees. So:

$\displaystyle \frac{3 \, rad}{1} \times \frac{180 \, degrees}{\pi \, rad} = \frac{540}{\pi}$ degrees $\displaystyle \approx 171.887338539$ degrees

So the reference angle is 180 - 171.887338539 = 8.112661461 degrees.

-Dan
• Oct 25th 2006, 04:30 PM
qbkr21
Re:
To be honest with you I know you multiply by (180/pi) however I am not looking for the measure in decimals, I could have done that, I am looking for it in terms of pi
• Oct 25th 2006, 05:28 PM
topsquark
Quote:

Originally Posted by qbkr21
To be honest with you I know you multiply by (180/pi) however I am not looking for the measure in decimals, I could have done that, I am looking for it in terms of pi

Then leave the angle in radians.

$\displaystyle \frac{\pi}{2} < 3 < \pi$

So the reference angle will be $\displaystyle \pi - 3$ rad.

-Dan
• Oct 25th 2006, 05:40 PM
qbkr21
Re:
Thanks sir it worked. OK I see how you got it now...