a+4=0

a+b=0

So: a=-4, b=4.

So: AO=BO=4

So: the triangle AOB is an isosceles right triangle.

Because it is perpendicular to AC, so: ABEO four corners * * * garden.

So: Angle OEG= Angle abalone =45.

So: angle AEO = 90 degrees-angle OEG = 45 degrees = angle OEG, that is, EO bisects angle AEG.

(2)

AO=BO

AC=BD

Angle Cao = angle

So: AOC of triangle is equal to BOD of triangle.

So: CO=DO

to be continued