Mark the tick against the correct answer in the following:
Let A be the set of all points in a plane and let O be the origin. Let R = {(P, Q) : OP = QQ}. Then, R is
According to the question ,
O is the origin
R = {(P, Q) : OP = OQ }
Formula
For a relation R in set A
Reflexive
The relation is reflexive if (a , a) ∈ R for every a ∈ A
Symmetric
The relation is Symmetric if (a , b) ∈ R , then (b , a) ∈ R
Transitive
Relation is Transitive if (a , b) ∈ R & (b , c) ∈ R , then (a , c) ∈ R
Equivalence
If the relation is reflexive , symmetric and transitive , it is an equivalence relation.
Check for reflexive
Consider , (P , P) ∈ R ⇔ OP = OP
which is always true .
Therefore , R is reflexive ……. (1)
Check for symmetric
(P , Q) ∈ R ⇔ OP = OQ
(Q , P) ∈ R ⇔ OQ = OP
Both the equation are the same and therefore will always be true.
Therefore , R is symmetric ……. (2)
Check for transitive
(P , Q) ∈ R ⇔ OP = OQ
(Q , R) ∈ R ⇔ OQ = OR
On adding these both equations, we get , OP = OR
Also,
(P , R) ∈ R ⇔ OP = OR
∴ It will always be true
Therefore , R is transitive ……. (3)
Now , according to the equations (1) , (2) , (3)
Correct option will be (D)