Fit data to a sinusoidal curve

Hi! I have two plots with data, they both look like a part of sinusoid. I have to prove that the changes in these two plots start at the same time by fitting a sinusoid to them. And then I have to make sure that they have the same sinusoidal period.

I am attaching the picture. So the first and the third plots in blue color are the ones that have to be fitted to a sinusoid. You can see that both lines start to change at the same time - the meanings are getting smaller.

How can I do this?

Thank you!

Answer 1

[Star Strider]

One option is to see if the approach in Curve fitting to a sinusoidal function does what you want.