Finding the length of angle bisectors

I can't seem to figure out the answer to these two problems, I have been trying to work on them with no luck. Could someone please explain to me how to do them, and which theorems are relevant to them. Thanks. (Cool)

4. In Triangle ABC , suppose that the bisector of angle B meets side AC at point E. If AB = 12, BC = 14, and AC = 18,

find AE and EC.

5. Given right triangle ABC with right angle at C, altitude CD is drawn to the hypotenuse of the triangle. If AD =

12 ,and DB = 4 3, find AC, CB, and CD.