Answer:
Lines which have
a point in common are said to be concurrent. In geometry, three or
more lines are said to be concurrent if they intersect at a single
point. In a triangle, four basic types of concurrent lines are altitudes,
angle bisectors, medians, and perpendicular bisectors.
 In a triangle, altitudes run from each vertex and meet the
opposite side at rightangles. The point where three altitudes
meet is the orthocenter
 Angle bisectors are rays running from the bisector of each
angle of the triangle. They all meet at the incenter.
 Medians connect the vertexes in a triangle to the midpoint
of the opposite side. They meet at the centroid
 Perpendicular bisectors are lines running out of the midpoint
of each side in a triangle at 90 degree angles. They meet at the
circumcenter.
