How to find the coodinates of the bounding rectangle from four circles around the vertices of an existing bounding rectangle

I have a bounding box which I have created. I know the lat lon of the four vertices of the box. On these vertices I have created a buffer circle of radius 10m and now I want to calculate a new bounding box which covers these four circles.

I have created four circles where I know the lat,lon of each points which makes the circle. How can I make and find the coordinates of the 4 ends of this new rectangle/bounding box which encloses these four circles in python.

Sample Image

For lat/lon aligned rectangle 10m distance correspond to angular shift

ltdiff = 180 * 10 / 20 000 000  = 0.00009

degrees along latitude

and

lndiff = 180 * 10 / 20 000 000 / cos(lat)  = 0.00009/cos(lat)

degrees along longitude

For example, for latitude 45n:

lndiff = 0.00009/cos(45) = 0.00009/0.7071 = 0.0001273 degrees

So expand you rectangle by these values (for small rectangles top and bottom latitude is nearly the same, so you can use the same value for cosine)

newtopleft.lat = topleft.lat - 0.00009 
newtopleft.lon = topleft.lon - 0.00009/cos(topleft.lat)
newtopright.lat = topright.lat - 0.00009 
newtopright.lon = topright.lon + 0.00009/cos(topright.lat)
similar for bottom left and right