any isosceles triangle
thank goodness for my math teacher, norm! he said only in an isosceles triangle. The bisector of the vertex angle of an isosceles triangle is perpendicular to the base! =)
iscoceles triangle! =)
Not always because a perpendicular bisector can be constructed with compasses
Not sure what an "irie" is. But a bisector does not need to be perpendicular.
Not always because the diagonals of a rectangle bisect each other but they are not perpendicular to each other.
The perpendicular bisectors only intersect on the triangle when it is an isosceles right triangle.
The angle bisectors always intersect inside the triangle. (This is not true for altitudes and right bisectors.)