A(4，0) B(8，4) C(0，4) D(4，4)

Linear AB equation: y=x-4

AC⊥AB, point e is on the straight line AB.

There are AC⊥AE and CG⊥GE.

So ACGE is a quarter circle.

Because of the same arc and equal angle

∠GCE=∠GAE=45

∠GAC=∠GEC=45

That is, ∠GCE=∠GEC.

So △GCE is isosceles, CG=GE.