IAT IISER2026MathematicsSets and Relations
Let C be the set of all the circles in a plane. If R = (C₁, C₂) C C C₁ and C₂ intersect , then which of the following statements is TRUE?
Options
- AR is reflexive and transitive but not symmetric.
- BR is not a relation.
- CR is symmetric and transitive but not reflexive.
- DR is reflexive and symmetric but not transitive.
Correct answer
D. R is reflexive and symmetric but not transitive.
Step-by-step solution
The relation R is defined as (C₁, C₂) R if C₁ and C₂ intersect. Reflexivity: For any circle C , the intersection of C with itself is C , which is non-empty ( C C = C ). Thus, C intersects itself, meaning (C, C) R . Therefore, R is reflexive. Symmetry: If C₁ intersects C₂ , then C₁ C₂ . This implies C₂ C₁ , so C₂ intersects C₁ . Thus, (C₁, C₂) R (C₂, C₁) R . Therefore, R is symmetric. Transitivity: Consider three circles C₁, C₂, C₃ of radius 1 centered at (0,0) , (2,0) , and (4,0) respectively. C₁ and C₂ intersect a