# Math Help - Graph of two sinusoids

1. ## Help please...Graph of two sinusoids

[Graph]
$y=3cos120pix+cos800pix$

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?

2. (deleted, merged into other post)

3. 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 $\cos nx$ can be found by $\frac{2\pi}{n}$

Originally Posted by wiseguy
[Graph]

Period of the shorter sinusoid: 0.016666
I think you mean = $\frac{1}{60}= 0.01\dot{6}$

4. So would the two periods be 0.016 and 0.0025? Or are the correct???