If the radius is 5, AB is 5 as well. If GB is 1, AG is 4. Use the pythagorean theorem to find the length of GD.
a² + b² = c²
a² + 4² = 5²
a² + 16 = 25
a² = 9
a = 3
This means GD is 3 and if EG is the same as GD, ED = 3 + 3, or 6 units
I hope this helps!