Home
Class 12
MATHS
Choose the correct answerThe value of in...

Choose the correct answerThe value of `int_0^(pi/2) log((4+3sinx)/(4+3cosx))dx`
(A) 2 (B) `3/4` (C) 0 (D) -2

A

`2`

B

`3/4`

C

`0`

D

`-2`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the integral \( I = \int_0^{\frac{\pi}{2}} \log\left(\frac{4 + 3 \sin x}{4 + 3 \cos x}\right) dx \), we will use a property of definite integrals and some logarithmic identities. ### Step-by-Step Solution: 1. **Define the Integral:** Let \( I = \int_0^{\frac{\pi}{2}} \log\left(\frac{4 + 3 \sin x}{4 + 3 \cos x}\right) dx \). 2. **Use the Property of Integrals:** We can use the property of integrals that states: \[ \int_0^a f(x) dx = \int_0^a f(a - x) dx \] Here, we will substitute \( x \) with \( \frac{\pi}{2} - x \): \[ I = \int_0^{\frac{\pi}{2}} \log\left(\frac{4 + 3 \sin\left(\frac{\pi}{2} - x\right)}{4 + 3 \cos\left(\frac{\pi}{2} - x\right)}\right) dx \] 3. **Simplify the Sine and Cosine:** Using the identities \( \sin\left(\frac{\pi}{2} - x\right) = \cos x \) and \( \cos\left(\frac{\pi}{2} - x\right) = \sin x \), we can rewrite the integral: \[ I = \int_0^{\frac{\pi}{2}} \log\left(\frac{4 + 3 \cos x}{4 + 3 \sin x}\right) dx \] 4. **Add the Two Integrals:** Now we have two expressions for \( I \): \[ I = \int_0^{\frac{\pi}{2}} \log\left(\frac{4 + 3 \sin x}{4 + 3 \cos x}\right) dx \] \[ I = \int_0^{\frac{\pi}{2}} \log\left(\frac{4 + 3 \cos x}{4 + 3 \sin x}\right) dx \] Adding these two equations gives: \[ 2I = \int_0^{\frac{\pi}{2}} \left( \log\left(\frac{4 + 3 \sin x}{4 + 3 \cos x}\right) + \log\left(\frac{4 + 3 \cos x}{4 + 3 \sin x}\right) \right) dx \] 5. **Combine the Logarithms:** Using the property \( \log a + \log b = \log(ab) \): \[ 2I = \int_0^{\frac{\pi}{2}} \log\left(\frac{(4 + 3 \sin x)(4 + 3 \cos x)}{(4 + 3 \cos x)(4 + 3 \sin x)}\right) dx \] This simplifies to: \[ 2I = \int_0^{\frac{\pi}{2}} \log(1) dx \] 6. **Evaluate the Integral:** Since \( \log(1) = 0 \): \[ 2I = \int_0^{\frac{\pi}{2}} 0 \, dx = 0 \] Therefore, we find: \[ I = 0 \] ### Conclusion: The value of the integral \( \int_0^{\frac{\pi}{2}} \log\left(\frac{4 + 3 \sin x}{4 + 3 \cos x}\right) dx \) is \( 0 \). ### Final Answer: The correct option is (C) \( 0 \).

To solve the integral \( I = \int_0^{\frac{\pi}{2}} \log\left(\frac{4 + 3 \sin x}{4 + 3 \cos x}\right) dx \), we will use a property of definite integrals and some logarithmic identities. ### Step-by-Step Solution: 1. **Define the Integral:** Let \( I = \int_0^{\frac{\pi}{2}} \log\left(\frac{4 + 3 \sin x}{4 + 3 \cos x}\right) dx \). 2. **Use the Property of Integrals:** ...
Doubtnut Promotions Banner Mobile Dark
|

Topper's Solved these Questions

  • INTEGRALS

    NCERT ENGLISH|Exercise EXERCISE 7.5|23 Videos
  • INTEGRALS

    NCERT ENGLISH|Exercise MISCELLANEOUS EXERCISE|44 Videos
  • INTEGRALS

    NCERT ENGLISH|Exercise EXERCISE 7.7|14 Videos
  • DIFFERENTIAL EQUATIONS

    NCERT ENGLISH|Exercise EXERCISE 9.1|12 Videos
  • INVERSE TRIGONOMETRIC FUNCTIONS

    NCERT ENGLISH|Exercise Solved Examples|13 Videos

Similar Questions

Explore conceptually related problems

Choose the correct answer The value of int0pi/2log((4-3sinx)/(4+3cosx))dx (A) 2 (B) 3/4 (C) 0 (D) -2

Evaluate: int_0^(pi/2)log((4+3sinx)/(4+3cosx))dx

Evaluate: int_0^(pi/2)log((4+3sinx)/(4+3cosx))dx

The value of int_(0)^(pi/2) log((4+3 sin x)/(4+3 cos x))dx , is

int_0^(pi/2) (dx)/(4+sinx)

Choose the correct answerThe Value of int_(-pi/2)^(pi/2)(x^3+xcosx+tan^5x+1)dx is(A) 0 (B) 2 (C) pi (D) 1

The value of I=int_0^(pi/2) (sinx+cosx)^2/sqrt(1+sin2x)dx is (A) 2 (B) 1 (C) 0 (D) 3

int_0^(pi/2) (3+4cosx)/(4+3cosx)^2dx= (A) 3/4 (B) 1/2 (C) pi/4 (D) 1/4

evaluate int_0^(pi/2) sinx/(sinx+cosx) dx

Evaluate: int_(-pi//2)^(pi//2)log(sinx+cosx)dx