Home
Class 12
MATHS
If cos (pi/12) = (sqrt(2) + sqrt(6))/(4)...

If `cos (pi/12) = (sqrt(2) + sqrt(6))/(4)`, then all `x in (0,pi/2)` such that `(sqrt(3)-1)/(sin x) + (sqrt(3)+1)/(cos x) = 4sqrt(2)`, then find x.

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem step by step, we need to find all values of \( x \) in the interval \( (0, \frac{\pi}{2}) \) such that: \[ \frac{\sqrt{3}-1}{\sin x} + \frac{\sqrt{3}+1}{\cos x} = 4\sqrt{2} \] ### Step 1: Rewrite the equation We start with the equation: \[ \frac{\sqrt{3}-1}{\sin x} + \frac{\sqrt{3}+1}{\cos x} = 4\sqrt{2} \] To combine the fractions, we take the common denominator \( \sin x \cos x \): \[ \frac{(\sqrt{3}-1)\cos x + (\sqrt{3}+1)\sin x}{\sin x \cos x} = 4\sqrt{2} \] ### Step 2: Cross-multiply Cross-multiplying gives us: \[ (\sqrt{3}-1)\cos x + (\sqrt{3}+1)\sin x = 4\sqrt{2} \sin x \cos x \] ### Step 3: Rearranging the equation Rearranging the equation, we have: \[ (\sqrt{3}-1)\cos x + (\sqrt{3}+1)\sin x - 4\sqrt{2} \sin x \cos x = 0 \] ### Step 4: Substitute values We know from the problem that \( \cos \frac{\pi}{12} = \frac{\sqrt{2} + \sqrt{6}}{4} \). We can use this information later if needed, but for now, we will continue with the equation. ### Step 5: Use the identity We can use the identity \( 2 \sin x \cos x = \sin(2x) \): \[ (\sqrt{3}-1)\cos x + (\sqrt{3}+1)\sin x = 2\sqrt{2} \sin(2x) \] ### Step 6: Factor and simplify We can express the left-hand side in terms of sine and cosine: Let \( A = \sqrt{3}-1 \) and \( B = \sqrt{3}+1 \): \[ A \cos x + B \sin x = 2\sqrt{2} \sin(2x) \] ### Step 7: Find the angle Using the sine addition formula, we can express \( A \cos x + B \sin x \) as: \[ R \sin(x + \phi) \] Where \( R = \sqrt{A^2 + B^2} \) and \( \tan \phi = \frac{B}{A} \). Calculating \( R \): \[ A^2 = (\sqrt{3}-1)^2 = 4 - 2\sqrt{3} \] \[ B^2 = (\sqrt{3}+1)^2 = 4 + 2\sqrt{3} \] \[ R^2 = A^2 + B^2 = (4 - 2\sqrt{3}) + (4 + 2\sqrt{3}) = 8 \] \[ R = 2\sqrt{2} \] ### Step 8: Set up the equation Now we have: \[ 2\sqrt{2} \sin(x + \phi) = 2\sqrt{2} \sin(2x) \] Dividing both sides by \( 2\sqrt{2} \): \[ \sin(x + \phi) = \sin(2x) \] ### Step 9: Solve for \( x \) This gives us two cases: 1. \( x + \phi = 2x + 2k\pi \) 2. \( x + \phi = \pi - 2x + 2k\pi \) For the first case: \[ \phi = x + 2k\pi \implies x = \phi - 2k\pi \] For the second case: \[ x + \phi = \pi - 2x + 2k\pi \implies 3x = \pi - \phi + 2k\pi \implies x = \frac{\pi - \phi + 2k\pi}{3} \] ### Step 10: Find specific values We will find \( \phi \) using \( \tan \phi = \frac{B}{A} = \frac{\sqrt{3}+1}{\sqrt{3}-1} \). Calculating \( \phi \) gives us: \[ \phi = \frac{\pi}{12} \] Thus, we can substitute back to find \( x \): 1. From the first case, \( x = \frac{\pi}{12} - 2k\pi \) (not in \( (0, \frac{\pi}{2}) \)). 2. From the second case, \( x = \frac{\pi - \frac{\pi}{12}}{3} = \frac{11\pi}{36} \). ### Final Answer The value of \( x \) in the interval \( (0, \frac{\pi}{2}) \) is: \[ \boxed{\frac{\pi}{12}} \]
Promotional Banner

Topper's Solved these Questions

  • TRIGNOMETRIC FUNCTIONS

    AAKASH INSTITUTE ENGLISH|Exercise Section - J (Akash Challengers Question)|16 Videos
  • TRIGNOMETRIC FUNCTIONS

    AAKASH INSTITUTE ENGLISH|Exercise Section -H (Multiple True-false, type Questions)|9 Videos
  • THREE DIMENSIONAL GEOMETRY

    AAKASH INSTITUTE ENGLISH|Exercise ASSIGNMENT SECTION - J|10 Videos
  • VECTOR ALGEBRA

    AAKASH INSTITUTE ENGLISH|Exercise SECTION-J (Aakash Challengers Questions)|5 Videos

Similar Questions

Explore conceptually related problems

The value of x in (0,pi/2) satisfying (sqrt(3)-1)/(sinx)+(sqrt(3)+1)/(cosx)=4sqrt(2) is / are

The value of x in (0,pi/2) satisfying the equation, (sqrt3-1)/sin x+ (sqrt3+1)/cosx=4sqrt2 is -

Prove that : int_(0)^(pi//2) (sqrt(cos x))/(sqrt(sin x+ sqrt(cos x)))dx=(pi)/(4)

Evaluate: int_0^(pi//2)(sqrt(sin x))/(sqrt(sin x)+sqrt(cos x))dx

If 4\ cos^(-1)x+sin^(-1)x=pi , then the value of x is (a) 3/2 (b) 1/(sqrt(2)) (c) (sqrt(3))/2 (d) 2/(sqrt(3))

The value of lim_(x->pi/4) (sqrt(1-sqrt(sin2x)))/(pi-4x) is

The value of lim_(x->pi/4) (sqrt(1-sqrt(sin2x)))/(pi-4x) is

lim_(x to 0) (sin^(2) x)/(sqrt(2)-sqrt(1+cos x))= (A) sqrt(2) (B) 2 (C) 4 (D) 4sqrt(2)

cos((3pi)/(4)+x)-cos((3pi)/(4)-x) = -sqrt(2)sinx

Prove that int_0^(pi/2) \ sin^2 x / (1+sin x cos x) \ dx = pi/(3 sqrt(3)

AAKASH INSTITUTE ENGLISH-TRIGNOMETRIC FUNCTIONS -Section I (subjective Type questions)
  1. If cos(alpha-beta)+cos(beta-gamma)+cos(gamma-alpha)=-3/2 , prove that ...

    Text Solution

    |

  2. If alpha and beta satisfy sinalpha cos beta=-1/2, then the greatest va...

    Text Solution

    |

  3. If cos (pi/12) = (sqrt(2) + sqrt(6))/(4), then all x in (0,pi/2) such ...

    Text Solution

    |

  4. In a DeltaABC if 3sinA+4 cosB=6, 4 sinB+3cosA=1 then possible value (s...

    Text Solution

    |

  5. If (4 cos^(2)9^(@)-3)(4 cos^(2)27^(@)-3) =tanK^(@) , then K is equal ...

    Text Solution

    |

  6. In triangle ABC, prove that the maximum value of tanA/2tanB/2tanC/2i s...

    Text Solution

    |

  7. In a Delta ABC, angle B lt angle C and the values of B and C satisfy t...

    Text Solution

    |

  8. If A ={ theta : 2cos^2 theta + sintheta <=2} , and B = {theta: pi/2<=t...

    Text Solution

    |

  9. Solve 4cot2theta=cot^2theta-tan^2theta

    Text Solution

    |

  10. If 3tan(theta-15^0)=tan(theta+15^0)0<theta<90^0 , find theta .

    Text Solution

    |

  11. If cos 2theta=(sqrt(2)+1)(cos theta-(1)/(sqrt(2))), then the general v...

    Text Solution

    |

  12. Solve the equation sin^(2)ntheta - sin^(2)(n-1)theta = sin^(2)theta

    Text Solution

    |

  13. Solve the equation tan x + (cosx)/(sqrt(1+sin2x))=2.

    Text Solution

    |

  14. Let x and y, (0 lt x, y lt pi/2) satisfy 3sin^(2)x + 2sin^(2)y=1 and 3...

    Text Solution

    |

  15. If angles A and B satisfy sqrt(2)cosA = cosB + cos^(3)B and sqrt(2)sin...

    Text Solution

    |

  16. Let the sum of all solutions of the equation 3sqrt(3) sin^(3)x + cos^...

    Text Solution

    |

  17. Solve the equation, 4^(sin2x + 2cos^(2)x+ 2sin^(2)x)=64.

    Text Solution

    |

  18. If the equation sin6x + cos4x=-2 have a family of nonnegative solution...

    Text Solution

    |

  19. Find all values of x, y and k for which the system of equations. sin...

    Text Solution

    |

  20. Solve for x and y if sqrt(sinx cosy)=0 and 2sin^(2)x - cos2y-2=0

    Text Solution

    |