# trig 1

• Jan 17th 2009, 08:08 AM
william
trig 1
Determine 2 positive and 2 negative principal angles for a terminal arm with a related acute angle of 20° in quadrant III.
• Jan 17th 2009, 11:02 AM
stapel
Quote:

Originally Posted by william
Determine 2 positive and 2 negative principal angles for a terminal arm with a related acute angle of 20° in quadrant III.

A "positive" angle will be one for which you went around the unit circle anti-clockwise. A "negative" angle will be one for which you went backward around the circle, or clock-wise.

What is your book's definition of a "principal angle" as related to an angle of the sort provided by this exercise? When you reply, please include a clear listing of your work and reasoning so far.

Thank you! :D
• Jan 17th 2009, 06:06 PM
william
Quote:

Originally Posted by stapel
A "positive" angle will be one for which you went around the unit circle anti-clockwise. A "negative" angle will be one for which you went backward around the circle, or clock-wise.

What is your book's definition of a "principal angle" as related to an angle of the sort provided by this exercise? When you reply, please include a clear listing of your work and reasoning so far.

Thank you! :D

principal angle- the angle between $0^o$ and $360^o$