# basic question

Discussion in 'Homework Help' started by bhuvanesh, Feb 17, 2015.

1. ### bhuvanesh Thread Starter Member

Aug 10, 2013
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Is there any difference between sin and sinusoidal signal? or are they same.Thank you

2. ### Kermit2 AAC Fanatic!

Feb 5, 2010
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sin is sin. sinusodial can be merely sin like and not a "pure" sinewave

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3. ### WBahn Moderator

Mar 31, 2012
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Depends on whether you make a distinction between a sine and a cosine signal.

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4. ### bhuvanesh Thread Starter Member

Aug 10, 2013
268
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do you mean that that sinusoidal is signal that looks similar like sine?

5. ### WBahn Moderator

Mar 31, 2012
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Have you looked up the definition of "sinusoidal" at all?

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6. ### bhuvanesh Thread Starter Member

Aug 10, 2013
268
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The sine wave or sinusoid is a mathematical curvethat describes a smooth repetitive oscillation. It is named after the function sine, of which it is the graph. It occurs often in pure and applied mathematics, as well as physics, engineering, signal processing and many other fields

But the above does not show any variation between sine and sinusoidal .Thank you

7. ### WBahn Moderator

Mar 31, 2012
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Quite the contrary, it pretty much states that "sine wave" and "sinusoid" are synonymous. But there is some fine print involved.

Do you make a distinction between a sine wave and a cosine wave?

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8. ### bhuvanesh Thread Starter Member

Aug 10, 2013
268
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yes off course i can make distinction with sin is odd signal and cosine is even signal. I can distinct in this way

9. ### WBahn Moderator

Mar 31, 2012
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Is that a sinewave or not?

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10. ### bhuvanesh Thread Starter Member

Aug 10, 2013
268
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now it becomes cosine signal!!!!!

11. ### WBahn Moderator

Mar 31, 2012
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It does?

Aren't sine and cosine 90° apart?

Ignoring the poor quality of the sketch, is this a sine wave?

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12. ### bhuvanesh Thread Starter Member

Aug 10, 2013
268
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looks like both

13. ### Kermit2 AAC Fanatic!

Feb 5, 2010
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conversely, ANY waveform can be described as a combination of two or more sinewaves

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14. ### Kermit2 AAC Fanatic!

Feb 5, 2010
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sine and cosine are the same "waveform", until time is relevant to the equation. the they become different from each other in phase only

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15. ### WBahn Moderator

Mar 31, 2012
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Good answer. The key point is that whether it is a "sine" wave or a "cosine" wave depends entirely on when you choose to start your clock (i.e., what point you choose as your reference point for the independent variable). The waveform itself is the same, so in that sense they are really the same signal, it's just how we express it relative to our arbitrarily chosen reference that differs.

So "sinusoid" is the generic term and applies to either sin() or cos() with an arbitrary phase angle. While sin() and cos() with zero phase angle can be viewed as being "different", but only if there is a specified reference point (i.e., t=0). Whether we make a distinction or not depends on the context of the discussion. We can break an arbitrary sinusoid into the sum of a sin() and cos() (with zero phase angle). In general, we can do this regardless of where we place our reference. This is known as decomposing them into a pair of quadrature-related signals.

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16. ### bhuvanesh Thread Starter Member

Aug 10, 2013
268
2
okay got the point,Thanks