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AP EAMCET · Maths · Trigonometric Ratios & Identities

The maximum and minimum values of the function f: defined by
fx=5cosx+3cosx+π3+8 for all x, are respectively

  1. A 15, 1
  2. B 8, -8
  3. C -7, -15
  4. D 1, -15
Verified Solution

Answer & Solution

Correct Answer

(A) 15, 1

Step-by-step Solution

Detailed explanation

Given, f(x)=5cosx+3cosx+π3+8 =5cosx+3cosxcosπ3-sinxsinπ3+8 =5cosx+3cosx12-sinx32+8 =5cosx+32cosx-332sinx+8 =132cosx-332sinx+8 Now, we know that Asinx+Bcosx∈-A2+B2,A2+B2 Here, we have A=132 and B=332 Therefore, -1322+3322+8≤fx≤1322+3322+8…