Step-by-step explanation:
can't really use the Pythagorean because you don't know this is a right triangle.
use the fact that they are similar
so
3/6 = x/12 where x is FE
cross multiply
6x = 36 therefore FE = 6
then 6/12 = y/9 where y is FD
cross multiply
12y = 54 = 54/12 therefore FD = 4.5
