Question

Name three undefined terms.
(A) Point
(B) Line
(C) Plane
(D) All of the above

Answer 1

Hint: In this question particularly, try to understand what undefined means. After that try to compare the definition of undefined and that of the individual term. You will easily come to know the terms which are defined and not defined. Compare each of the given terms individually.

Complete answer:
We will start the solution by stating what Undefined terms are. Undefined terms in mathematics usually mean the terms which are not formally defined in geometry.We will start checking which of the above terms are undefined one by one by their description in geometry.

Starting with point, a point has been never known to have dimension. That is a point has no length, breadth or thickness. Even though it is represented as a dot there is no specific way of representing the dot. Hence point is an undefined term.A Line in this case has dimension. That is it’s length extends in one dimension.

But the thickness of the line cannot be determined nor the length. Hence Line is also undefined term.A plane similar to that of a line has no thickness i.e. the thickness of its edges cannot be determined. Also it can be extended indefinitely in any direction. Hence the plane is undefined.Hence we can conclude all three terms are undefined.

Hence the correct answer is option D.

Note: When questions of this type are given try to directly start comparing with the parts that both definitions have in common. This will help us to actually find if the terms are defined or not. These types of questions do not need any formula and there are no expectations of any pattern in the solution.