# Graph of two sinusoids

• Jul 23rd 2010, 10:21 AM
wiseguy
Help please...Graph of two sinusoids
[Graph]
$\displaystyle y=3cos120pix+cos800pix$

Period of the longer sinusoid: 0.05
Period of the shorter sinusoid: 0.016666
Frequency of the longer sinusoid: 20 cycles
Frequency of the shorter sinusoid: 60 cycles

I'm taking a bit of a shot in the dark on this one... does it look correct?
• Jul 23rd 2010, 08:17 PM
wiseguy
(deleted, merged into other post)
• Jul 23rd 2010, 10:41 PM
pickslides
Quote:

Originally Posted by wiseguy
[Graph]

Period of the longer sinusoid: 0.05
Period of the shorter sinusoid: 0.016666

These answers worry me, which of the two summed functions do you think is longer?

Period for $\displaystyle \cos nx$ can be found by $\displaystyle \frac{2\pi}{n}$

Quote:

Originally Posted by wiseguy
[Graph]

Period of the shorter sinusoid: 0.016666

I think you mean = $\displaystyle \frac{1}{60}= 0.01\dot{6}$
• Jul 24th 2010, 06:50 AM
wiseguy
So would the two periods be 0.016 and 0.0025? Or are the correct???