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JEE Main 202330 JanuaryMorning Shift
Exam
JEE Main
Year
2023
Date
30 January
Shift
Morning Shift
Subject
Mathematics
Chapter
Basics of Mathematics

JEE Main 2023 · 30 January · Morning Shift · Mathematics · Basics of Mathematics

If the solution of the equation _ x ( x) + 4 _ x ( x) = 1, x ∈ (0,...

If the solution of the equation log⁡cos⁡x(cot⁡x)+4log⁡sin⁡x(tan⁡x)=1,x∈(0,π2)\log_{\cos x}\left(\cot x\right) + 4\log_{\sin x}\left(\tan x\right) = 1, x \in \left(0, \dfrac{\pi}{2}\right) is sin⁡−1(α+β2)\sin^{- 1}\left(\dfrac{\alpha + \sqrt{\beta}}{2}\right), where α,β\alpha, \beta are integers, then α+β\alpha + \beta is equal to:

Options

  1. A33
  2. B55
  3. C66
  4. D44

Correct answer

D. 44

Step-by-step solution

Given:

log⁡cos⁡x(cot⁡x)+4log⁡sin⁡x(tan⁡x)=1,x∈(0,π2)\log_{\cos x}\left(\cot x\right) + 4\log_{\sin x}\left(\tan x\right) = 1, x \in \left(0, \dfrac{\pi}{2}\right)

⇒ln⁡cos⁡x−ln⁡sin⁡xln⁡cos⁡x+4(ln⁡sin⁡x−ln⁡cos⁡xln⁡sin⁡x)=1⇒ \dfrac{\ln \cos x - \ln \sin x}{\ln \cos x} + 4\left(\dfrac{\ln \sin x - \ln \cos x}{\ln \sin x}\right) = 1

⇒1−(ln⁡sin⁡xln⁡cos⁡x)+4(1−ln⁡cos⁡xln⁡sin⁡x)=1⇒ 1 - \left(\dfrac{\ln \sin x}{\ln \cos x}\right) + 4\left(1 - \dfrac{\ln \cos x}{\ln \sin x}\right) = 1

⇒(ln⁡sin⁡xln⁡cos⁡x)+4(ln⁡cos⁡xln⁡sin⁡x)−4=0⇒ \left(\dfrac{\ln \sin x}{\ln \cos x}\right) + 4\left(\dfrac{\ln \cos x}{\ln \sin x}\right) - 4 = 0

⇒(ln⁡sin⁡x)2−4(ln⁡sin⁡x)(ln⁡cos⁡x)+4(ln⁡cos⁡x)2=0⇒ ( \ln \sin x{)}^{2} - 4 ( \ln \sin x ) ( \ln \cos x ) + 4 ( \ln \cos x{)}^{2} = 0

⇒(ln⁡sin⁡x−2ln⁡cos⁡x)2=0⇒ {\left(\ln \sin x - 2\ln \cos x\right)}^{2} = 0

⇒ln⁡sin⁡x=2ln⁡cos⁡x⇒ \ln \sin x = 2\ln \cos x

⇒ln⁡sin⁡x=ln⁡cos⁡2x⇒ \ln \sin x = \ln\cos^{2} x

⇒cos⁡2x=sin⁡x⇒ \cos^{2}x = \sin x

⇒1−sin⁡2x=sin⁡x⇒ 1 - \sin^{2}x = \sin x

⇒sin⁡2x+sin⁡x−1=0⇒ \sin^{2}x + \sin x - 1 = 0

⇒sin⁡x=−1+52⇒ \sin x = \dfrac{- 1 + \sqrt{5}}{2}

So, α=−1,β=5\alpha = - 1, \beta = 5

∴α+β=4∴ \alpha + \beta = 4

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