Hello to everyone

I need help about Lag low pass compansator. I am using low pass filter but I do not know its cut off frequency calculation. Is there anyone who can describe it in mathematical formula.

I wonder that lag compansator cut off frequency and effects of R2 to it except for improved stability. Link is below

http://www.electrical4u.com/compensation-in-control-system-lag-lead-compensation/

 

The equations are shown in your referenced article.
What more do you need?
Are you wondering what corner frequencies to use for an actual application?

 

Sounds a bit more like homework than natural curiosity.