Triangle a b c is shown. lines are drawn from each point to the opposite side and intersect at point d. they form line segments a g, b e, and c f. in the diagram, which must be true for point d to be an orthocenter? be, cf, and ag are angle bisectors. be ⊥ ac, ag ⊥ bc, and cf ⊥ ab. be bisects ac, cf bisects ab, and ag bisects bc. be is a perpendicular bisector of ac, cf is a perpendicular bisector of ab, and ag is a perpendicular bisector of bc.