Answer:
DG=16 m
Step-by-step explanation:
Given: AD, BD and Cd are the angle bisectors of the sides of ΔABC and B=12m and BD=20m.
To find: The value of DG.
Solution: It is given that AD, BD and Cd are the angle bisectors of the sides of ΔABC and B=12m and BD=20m, then from the ΔBED, we have

Substituting the given values, we have





Thus, the value of ED is 16m.
Now, we know that the distance from the mid points of the sides of the given triangle to the circumcenter D are equal, thus
ED=DG
ED=DG=16
Therefore, the value of DG is 16m.