altitude
a segment from a vertex to the line containing the opposite side and perpendicular to the line containing that side
centroid
the point of concurrency for the median of a triangle
circumcenter
the point of concurrency of the perpendicular bisectors of a triangle
concurrent lines
three or more lines and their point of intersection
incenter
the point of concurrency of the angle bisectors of a triangle
median
a line segment with endpoints that are a vertex of a triangle and the midpoint of the side opposite the vertex
orthocenter
the point of concurrency of the altitudes of a triangle
perpendicular bisector
a line, segment, or ray that passes through the midpoint of a side and its perpendicular to that side
point of concurrency
the point of intersection of concurrent lines