How to get the latitude and longitude point by shifting fixed distance (for google map scanning window)?

I want to search some stores in a country, for example:

Find all Nike stores in US.

I implement it by using Google Map Place API. However I found that Google API seems not allowed to search a target that located in specific country, and it also restrict the searching radius (50000 meters).

So, I’m now trying to use "scan window" as below, which is the most feasible way I can figure out.

enter image description here

The main concept is to give two point with latitude and longitude (blue point in img) to make a plane, and the program would slice this area into many small circle with fixed radius. And then we can use the center of each circle (the red point) to query the Google API.

But when I’m working with the slicing function, I have know idea how to get these red points if I want to shift a point by distance…

Does anyone knows how to implement this function ? Or is there any other way to achieve my goal ?

Thanks a lot.

Source: Python-3x Questions