# Complex waveform

1. Mar 23, 2014

### anthonyk2013

Having some trouble with this question,

A complex wave is described by equation, y=100 sin ωt+30 sin(3ωt-∏/2)
A) on the same axis sketch and label,
1)one cycle of the fundamental waveform
2)the third harmonic
3) the complex waveform(y)

ω=2∏f
T=2∏/ω

Not sure where to start.
To sketch graph I need to find time, to get time I need frequency. Not sure how to find frequency from 100 sin ωt
as
Do I just treat ω as 2∏?

Last edited: Mar 23, 2014
2. Mar 23, 2014

### BvU

No, you treat $\omega\, t$ as the x coordinate.

3. Mar 23, 2014

### anthonyk2013

Ok so I have ωt, ωt/2, ωt/3 along my x axis for my time coordinates ?

Last edited: Mar 23, 2014
4. Mar 23, 2014

### BvU

No, just $\omega \, t$

5. Mar 23, 2014

### BvU

If you still feel uncomfortable, choose $\omega = 1$, make the y, t plot and then rename the t axis to $\omega t$ axis !

6. Mar 23, 2014

### anthonyk2013

Where i'm getting confused is i'm used to solving the likes of 100 sin (100 ∏ t)

from there you get time=20ms, so you can plot the time axis up to 20ms.

I don't understand how to plot ωt

7. Mar 24, 2014

### BvU

Perhaps I confused you earlier on, sorry. There is no solving involved, just plotting. One period in A1 -- so from $100 \, \omega\, t=0$ to $100\, \omega\, t=2\pi$

#### Attached Files:

• ###### Sine100wt.jpg
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8. Mar 24, 2014

### anthonyk2013

I understand now cheers.