मराठी

Let L Be the Set of All Lines in Xy-plane and R Be the Relation in L Defined as R = {L1, L2) : L1 is Parallel to L2}. Show that R is an Equivalence Relation. Find the Set of All Lines Related to the L

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प्रश्न

Let L be the set of all lines in XY-plane and R be the relation in L defined as R = {L1, L2) : L1 is parallel to L2}. Show that R is an equivalence relation. Find the set of all lines related to the line y= 2x + 4.

बेरीज
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उत्तर

We observe the following properties of R.

Reflexivity: Let L1 be an arbitrary element of the set L. Then,

L1 ∈ L

⇒ L1 is parallel to L1              [Every line is parallel to itself]

⇒ (L1, L1) ∈ R  for all L1 ∈ L

So, R is reflexive on L.

Symmetry : Let (L1, L2) ∈ R

⇒ L1  is parallel to L2

⇒ L2  is parallel to L1

⇒ (L2, L1) ∈ R  for all L1 and L2 ∈ L

So, R is symmetric on L.

Transitivity : Let (L1, L2) and (L2, L3) ∈ R

⇒ L1  is parallel to L2  and L2  is parallel to L3

⇒ L1, L2 and L3 are all parallel to each other

⇒L1 is parallel to L3

⇒(L1, L3) ∈ R

So, R is transitive on L.

Hence, R is an equivalence relation on L.

Set of all the lines related to y = 2x+4
                                                 = L' = {(x, y) : y = 2x+c, where c∈ R}

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पाठ 1: Relations - Exercise 1.2 [पृष्ठ २७]

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आर.डी. शर्मा Mathematics Volume 1 and 2 [English] Class 12
पाठ 1 Relations
Exercise 1.2 | Q 9 | पृष्ठ २७

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