May 11th, 2018, 09:23 PM  #1 
Member Joined: Aug 2017 From: India Posts: 50 Thanks: 2  Negative Theta Angle
If you take a circle, the angle theta varies from 0 to 360 Degrees. What exactly is negative angle like 30 etc? I mean to say 330 is also 30 degrees? I am confused?
Last edited by skipjack; May 12th, 2018 at 06:34 AM. 
May 11th, 2018, 09:57 PM  #2 
Global Moderator Joined: Oct 2008 From: London, Ontario, Canada  The Forest City Posts: 7,912 Thanks: 1110 Math Focus: Elementary mathematics and beyond 
The sign of an angle is generally taken to be the direction from 0$^\circ$ with a negative value indicating clockwise motion.

May 11th, 2018, 10:16 PM  #3 
Member Joined: Aug 2017 From: India Posts: 50 Thanks: 2 
So if I correctly understand, 0 to 360 degrees is counter clockwise direction and 0 to 360 (20 etc.) is clockwise direction. Am I correct?
Last edited by skipjack; May 12th, 2018 at 06:19 AM. 
May 11th, 2018, 10:24 PM  #4 
Senior Member Joined: Nov 2010 From: Indonesia Posts: 2,001 Thanks: 132 Math Focus: Trigonometry  Yes.
Last edited by skipjack; May 12th, 2018 at 06:19 AM. 
May 11th, 2018, 10:29 PM  #5 
Global Moderator Joined: Oct 2008 From: London, Ontario, Canada  The Forest City Posts: 7,912 Thanks: 1110 Math Focus: Elementary mathematics and beyond  Yes. So $\cos270^\circ=\cos90^\circ$ or, more generally, $\cos\alpha=\cos(\alpha+360k),k\in\mathbb{Z}$.
Last edited by skipjack; May 12th, 2018 at 06:19 AM. 
May 12th, 2018, 06:34 AM  #6 
Global Moderator Joined: Dec 2006 Posts: 20,274 Thanks: 1959  
May 12th, 2018, 08:02 PM  #7 
Member Joined: Aug 2017 From: India Posts: 50 Thanks: 2  Is it possible for you to give examples or links corresponding to them? Thank you.
Last edited by greg1313; May 12th, 2018 at 08:20 PM. 
May 14th, 2018, 03:24 AM  #9 
Member Joined: Aug 2017 From: India Posts: 50 Thanks: 2 
My requirement is a kind of creation of sine wave using a look up table. So the 360 degrees is represented as 65536 an int value. The sampling frequency is the frequency of the pwm signal which 20KHz. I need to write a program for the same. I do not know what is the use of this sampling frequency. Why is it required? Please advise.


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