Which is precisely defined using the undefined terms point and plane?

Which is precisely defined using the undefined terms point and plane?

A. circle

B. line segment

C. perpendicular lines

D. ray

Answer: D. ray

A ray is defined with timelessness using only definitions of the undefined terms point and plane. In geometry, some ideas cannot be defined and are used as basic ideas on which other shapes can be defined for example point and plane. Indeed, a ray is one of the concepts that can be defined with a considerable degree of rigor making use of these basic elements.

Ray can be described as a line segment that has its end point marked and goes infinitely in one direction in a plane. This definition is most elementary as it makes use of only two ideas, that of point and that of plane. For instance, let a point A in a plane. From this point, one can draw a line, and this can go on for as long as possible in one line only. This extension together with the starting point A makes the figure a ray. Thus, the main characteristics of a ray are the fixed starting point and the infinite length in one direction, and both of these can be defined with the help of points and planes only.

On the other hand, other options such as circles, line segments and perpendicular lines include other concepts or measurements in their definitions. Distance is needed for the definition of the points equally distant from the centre of the circle. A line segment has two specified points and the idea of having a finite length. Perpendicular lines are involved with the angle. Thus, the definition of a ray is more basic as it involves only the undefined terms of a point and a plane as against the segment that involved the line as one of its undefined terms used in the definition.