Select justification as to use ser or estar? Please help me answer this question.

What did the mexican solders eat during 1833

In the diagram, which must be true for point d to be anorthocenter? o be, cf, and ag are angle bisectors.be 1 ac, ag 1 bc, and cf 1 ab.be bisects ac, cf bisects ab, and ag bisects bc.be is a perpendicular bisector of ac, cf is aperpendicular bisector of ab, and ag is a perpendicularbisector of bc.

Does anyone know how to do this and can urgant it was due like 2 weeks ago