Comparing Matrices (D3D9)

hey, just a stupid question, im new to D3D, previously just ben coding 2D games using Dx7 and the GDI but i decided id make the change to 3D, im reading through a D3D book and im at the part of handling transformations and translations allowing roatation and movement of primitives using matrices. now logicaly i thought, hey if matrices hold position data then surely comparing matrices could tell me if two primitives are coliding or not, so i skimmed the book looking to see if it had any info on collision and to my annoyance not a thing on collision detection in the whole book..

can any 1 point me in the right direction?

thanx