# Reference Angles...

• August 15th 2008, 01:28 PM
topaz192
Reference Angles...
I just want to know if i did this right. the directions were to find the measure of the reference angle for each angle.

563 degrees.

When it comes to rational fraction how do you know what numbers to use to subtracrt?

For this problem I just did 563 - 360 = 203.

Is that all Im suppose to do?

• August 15th 2008, 01:54 PM
Chop Suey
No, that is not what you are supposed to do. You need to find the reference angle of 203.

In degrees:
For angles in 1st Quadrant: $0 < \theta < 90$ $\theta_{ref} = \theta$

For angles in 2nd Quadrant: $90< \theta <180: \theta_{ref} = 180 - \theta
$

For angles in 3rd Quadrant: $180 < \theta < 270: \theta_{ref} = \theta - 180$

For angles in 4th Quadrant: $270< \theta < 360:$ $\theta_{ref} = 360 - \theta$
• August 15th 2008, 02:16 PM
topaz192
So find the reference angle for 203??

Idk its hard for me to get because the usual problems are already in between 90 degrees and 180.

EX: 120 degrees

Since its already inbetween the ending [or terminal] will be in the 2nd quadrant...sooo i did 180 - 120 which gave me 60.

So does that mean i need to find 60 too? (Wait)
• August 15th 2008, 02:27 PM
Chop Suey
563-360 = 203

563 and 203 are coterminal angles, which means they have the same terminal sides. The reason why we subtracted 360 from 563 is to get the angle between 0 and 360. Once we have done that, we can easily find the reference angle that way.

I told you how to find the reference angle for 203. Notice that it is in the third quadrant because the angle is between 180 and 270. The relation between the reference angle and the 3rd Quadrant angle is:

$\theta_{ref} = \theta - 180$
$\theta_{ref} = 203 - 180$
...
• August 15th 2008, 11:56 PM
topaz192
Oh ok! lol Thanks soooo much for your time! (Clapping)