Cutter compensation

When I select cutter compensation to the left or the right what is
the equation the cnc control computes. And when it rounds accute line
angles with a rad what angles does this work on. For example

G00 x0 Y0
G01 x5 y0
G01 x5 y5
G01 x0 y0

For the above program if I wanted tool comp to the left using a 6mm
dia tool what would be the new points if i were to program using no
tool comp.

Any help would be most appriated.

cheers

Sid