[color=#c51414]Ceva's Theorem[/color] is the criteria for determining the congruence of cevians of a triangle. Cevians are [b]line segments[/b] or [b]rays[/b] that extend from a given vertex to the opposite side such as [color=#1551b5]medians, altitudes, and angle bisectors[/color]. Cevians are not always found within the triangle. The theorem states that in triangle ABC with points D, E, and F respectively on lines BC, CA, and AB, lines AD, BE, and CF are [color=#1551b5]congruent[/color] if and only if the below ratios multiplied equal [b]1[/b].