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Class 12 Inverse Trigonometric Functions · Assertion Reason1 Marksassertion_reason

Class 12 Maths · Inverse Trigonometric Functions · Assertion Reason #28

Assertion: The function f:R→R, f(x)=cos x, is bijective. Reason: If g:A→B is bijective, there exists h:B→A with g∘h=id_B and h∘g=id_A.

✅ Step-by-Step Solution

Final Answer: Option (D): A is false, but R is true.
  1. Cosine is not injective, for example cos0=cos2π; its range is [−1,1], so it is not onto R. The stated inverse-function property of a bijection is true.

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