Analytic Geometry 3D

Question

Hallo

 

How to ?

 

1. find intersection two line in 3D (with X,Y,Z coord) ?

 know Point A (Xa, Ya, Za) and point B (Xb,Yb,Zb)

 

2. find intersection line and spher 3D ?

know Point A (Xa, Ya, Za) and center sphere point B (Xb,Yb,Zb) with radius

3. find intersection between two sphers ?

know center spherePoint A (Xa, Ya, Za) and center sphere point B (Xb,Yb,Zb) with radius 

 

4. find intersection between three spheres ?

 

i need code, algorythm, manual, links

 

Thanks