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For any two real number a b and , we defined aRb if and only if sin2a + cos2b = 1. The relation R is(a) reflexive but not symmetric (b) symmetric but not transitive (c) transitive but not reflexive (d) an equivalence relation |
Answer» (d) an equivalence relation Given, a R b ⇒ sin2a + cos2b = 1 Reflexive: a R a ⇒ sin2 a + cos2 a = 1 ∀ a ∈ R (True) Symmetric: a R b ⇒ sin2 a + cos2 b = 1 ⇒ 1 – cos2 a + 1 – sin2 b = 1 ⇒ sin2 b + cos2 a = 1 ⇒ b R a ∀ a, b ∈ R (True) Transitive: a R a and b R c ⇒ sin2 a + cos2 b = 1 and sin2 b + cos2 c = 1 ∴ Adding these two equations we get sin2 a + cos2 b + sin2 b + cos2 c = 2 ⇒ sin2 a + cos2 c = 1 ⇒ a R c (True) ∴ R is an equivalence relation. |
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