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Class 12 Inverse Trigonometric Functions · Short Answer2 Marksbranch_sensitive_simplification

Class 12 Maths · Inverse Trigonometric Functions · Short Answer #57

For \(-3\pi/2<x<\pi/2\), simplify \(\tan^{-1}[\cos x/(1-\sin x)]\).

✅ Step-by-Step Solution

Final Answer: π/4+x/2
  1. The half-angle identity gives cos x/(1−sin x)=tan(π/4+x/2); the denominator is nonzero on the stated open interval.
  2. The interval implies −π/2<π/4+x/2<π/2, so this angle lies in the principal arctangent range.
  3. Thus the expression equals π/4+x/2.

📋 CBSE Stepwise Marking Scheme

  • [0.5 marks] The half-angle identity gives cos x/(1−sin x)=tan(π/4+x/2); the denominator is nonzero on the stated open interval.
  • [1 mark] The interval implies −π/2<π/4+x/2<π/2, so this angle lies in the principal arctangent range.
  • [0.5 marks] Thus the expression equals π/4+x/2.

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