Explain why there must be at least two lines on any given plane.

Answer:

A plane contains at least three noncollinear points. According to geometric postulates, any two distinct points define a unique line. Since the three points in the plane are noncollinear, they cannot all lie on the same line. By connecting different pairs of these points (for example, point A to point B and point B to point C), at least two distinct lines are formed within the plane.