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.