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Class 12 Applications Of Derivatives · Short Answer2 Marksabsolute_extrema

Class 12 Maths · Applications Of Derivatives · Short Answer #95

Prove that f(x)=sin x+√3cos x has a maximum at x=π/6, and find that value.

✅ Step-by-Step Solution

Final Answer: Maximum 2 at x=π/6 (also π/6+2kπ).
  1. Use the identity sin x+√3cos x=2sin(x+π/3).
  2. Since sin u≤1, f≤2, with equality when x+π/3=π/2+2kπ.
  3. The maximum 2 occurs at x=π/6+2kπ, including x=π/6.

📋 CBSE Stepwise Marking Scheme

  • [0.5 marks] Use the identity sin x+√3cos x=2sin(x+π/3).
  • [1 mark] Since sin u≤1, f≤2, with equality when x+π/3=π/2+2kπ.
  • [0.5 marks] The maximum 2 occurs at x=π/6+2kπ, including x=π/6.

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