cartesian coordinates / two circles

hello,

I have two circles with **known** r1 & r2 radii.

I **know **the centers cartesian coordinates C0(a0,b0) & C1(a1,b1).

I **know** the distance "d" between centers of Circle 1 & Circle 2

(circles never overlap in my problem)

Then, i have (the **two blue lines**) like in this picture :

[IMG] http://img180.imageshack.us/img180/6710/twocircles.png [/IMG]

These 2 blue lines are **common tangent lines**

(interior tangent & exterior tangent) **to those two circles**.

I **really need to find out** the cartesian coordinates of :

case A (exterior tangent):

T0(x0,y0) = ?

T1(x1,y1) = ?

case B (interior tangent):

T2(x2,y2) = ?

T3(x3,y3) = ?

i.e , find for example for T0 point , x0 = ??? and y0 = ???

Please help, im not so good at math , need this in a very little game im trying to make.

**Really appreciate your help .**

**note**: this is use in a very little game im trying to make :)