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May 11th, 2018, 08:23 PM   #1
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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 05:34 AM.
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May 11th, 2018, 08:57 PM   #2
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The sign of an angle is generally taken to be the direction from 0$^\circ$ with a negative value indicating clockwise motion.
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May 11th, 2018, 09:16 PM   #3
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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 05:19 AM.
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May 11th, 2018, 09:24 PM   #4
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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?
Yes.

Last edited by skipjack; May 12th, 2018 at 05:19 AM.
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May 11th, 2018, 09:29 PM   #5
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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?
Yes. So $\cos270^\circ=\cos-90^\circ$ or, more generally, $\cos\alpha=\cos(\alpha+360k),k\in\mathbb{Z}$.

Last edited by skipjack; May 12th, 2018 at 05:19 AM.
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May 12th, 2018, 05:34 AM   #6
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Quote:
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If you take a circle, the angle theta varies from 0 to 360 Degrees.
That's a usable convention for polar coordinates, but other conventions are possible. A function of the angle needn't have 0 to 360 degrees as its domain, and needn't be periodic.
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May 12th, 2018, 07:02 PM   #7
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Quote:
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That's a usable convention for polar coordinates, but other conventions are possible. A function of the angle needn't have 0 to 360 degrees as its domain, and needn't be periodic.
Is it possible for you to give examples or links corresponding to them? Thank you.

Last edited by greg1313; May 12th, 2018 at 07:20 PM.
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May 13th, 2018, 03:18 AM   #8
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You can find more detail and examples here.
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May 14th, 2018, 02:24 AM   #9
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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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