Here are two circles. Their centers are and . The first figure is a circle with center A and points E, C, B, and D lie on the circle. A line segment extends from A to point D and a second line segment extends from A to point C, where line segment AC is labeled 4 centimeters. A third line segment is extends from point E to point B, where line segment EB goes through point A. The second figure is a circle with center F and points H and G lie on the circle. A line segment is extends from point H to point G where line segment HG goes through point F and is labeled 8 centimeters.

What is the length of segment ?