vectors

1) if A(1,-1,3) B(2,1,-2) C(-5,2,-6) are the vertices of a triangle ABC , then the length of internal angular bisctor of angle A is??

2)the median AD of triangle ABC is bisected at E and BE meets AC at F then AF:FC ???

3)if x and y are two non collinear vectors and tri ABC with sides a,b,c satisfying (20a-15b)x^ + (12c-20a)y^ + (12c-20a)(x^ x y^) = 0^ then trigle ABC is ?

anyone pls can help me atleast one f them