Geometry Triangle Terms

Concurrent lines

three or more lines that intersect in the same point; the point of intersection is called the point of concurrency

Centroid

the point of intersection of three medians of

a triangle; a centroid divides each median into a ratio of 2:1

Circumcenter

point of intersection of the three perpendicular bisectors of three sides of a triangle; this point is equidistant from the vertices of a triangle; the meet; circumcenter can fall in the interior or exterior of a triangle

A circle can be circumscribed about a triangle that contains a circumcenter

Incenter

the point of intersection of three angle bisectors of a triangle; each are equidistant from the sides of the triangle and always lie in the interior of the triangle

A circle can be inscribed within a triangle that contains a incenter

Orthocenter

The point of intersection of the altitudes (heights) of a triangle; in an acute triangle the orthocenter is in the interior of the triangle; in a right triangle the orthocenter is at the vertex of the right angle; in an obtuse triangle the orthocenter is in the exterior of the triangle.

Median of Triangle

A median of a triangle is a line segment from a vertex to the midpoint of the opposite side; a median bisects the line segment.

Angle Bisector

An angle bisector of a triangle is a line segment that bisects an angle; an angle bisector bisects an angle

Altitude of Triangle

An altitude of a triangle is a line segment from a vertex to a base; it is perpendicular to the base (it forms right angles with the base)

Perpendicular bisector

perpendicular bisector of a triangle is a line segment which is perpendicular to a line segment and bisects the line segment.