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The values of x in (0, pi) satisfying th...

The values of x in `(0, pi)` satisfying the equation.
`|{:(1+"sin"^(2)x, "sin"^(2)x, "sin"^(2)x), ("cos"^(2)x, 1+"cos"^(2)x, "cos"^(2)x), (4"sin" 2x, 4"sin"2x, 1+4"sin" 2x):}| = 0`, are

A

`(pi)/(12), (7pi)/(12)`

B

`(5pi)/(12), (7pi)/(12)`

C

`(7pi)/(12), (11pi)/(12)`

D

`(pi)/(12), (11pi)/(12)`

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To solve the equation given by the determinant: \[ \begin{vmatrix} 1 + \sin^2 x & \sin^2 x & \sin^2 x \\ \cos^2 x & 1 + \cos^2 x & \cos^2 x \\ 4 \sin 2x & 4 \sin 2x & 1 + 4 \sin 2x \end{vmatrix} = 0 \] we will follow these steps: ### Step 1: Apply Determinant Properties We will simplify the determinant by applying the property of determinants where we can subtract one column from another. We will perform the following operations: - Column 1 (C1) = C1 - C3 - Column 2 (C2) = C2 - C3 After applying these operations, the determinant becomes: \[ \begin{vmatrix} 1 + \sin^2 x - \sin^2 x & \sin^2 x - \sin^2 x & \sin^2 x \\ \cos^2 x - \cos^2 x & 1 + \cos^2 x - \cos^2 x & \cos^2 x \\ 4 \sin 2x - 4 \sin 2x & 4 \sin 2x - (1 + 4 \sin 2x) & 1 + 4 \sin 2x \end{vmatrix} \] This simplifies to: \[ \begin{vmatrix} 1 & 0 & \sin^2 x \\ 0 & 1 & \cos^2 x \\ 0 & -1 & 1 + 4 \sin 2x \end{vmatrix} \] ### Step 2: Expand the Determinant Now, we can expand the determinant along the first row: \[ = 1 \cdot \begin{vmatrix} 1 & \cos^2 x \\ -1 & 1 + 4 \sin 2x \end{vmatrix} \] Calculating the 2x2 determinant: \[ = 1 \cdot (1 \cdot (1 + 4 \sin 2x) - (-1) \cdot \cos^2 x) \] \[ = 1 + 4 \sin 2x + \cos^2 x \] ### Step 3: Set the Determinant to Zero Now we set the expanded determinant equal to zero: \[ 1 + 4 \sin 2x + \cos^2 x = 0 \] Using the identity \(\cos^2 x = 1 - \sin^2 x\): \[ 1 + 4 \sin 2x + (1 - \sin^2 x) = 0 \] \[ 2 + 4 \sin 2x - \sin^2 x = 0 \] ### Step 4: Substitute \(\sin 2x\) Recall that \(\sin 2x = 2 \sin x \cos x\). We can express \(\sin^2 x\) in terms of \(\sin 2x\): Let \(y = \sin 2x\): \[ 2 + 4y - \frac{y^2}{4} = 0 \] Multiplying through by 4 to eliminate the fraction: \[ 8 + 16y - y^2 = 0 \] \[ y^2 - 16y - 8 = 0 \] ### Step 5: Solve the Quadratic Equation Using the quadratic formula \(y = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\): Here, \(a = 1\), \(b = -16\), and \(c = -8\): \[ y = \frac{16 \pm \sqrt{(-16)^2 - 4 \cdot 1 \cdot (-8)}}{2 \cdot 1} \] \[ = \frac{16 \pm \sqrt{256 + 32}}{2} \] \[ = \frac{16 \pm \sqrt{288}}{2} \] \[ = \frac{16 \pm 12\sqrt{2}}{2} \] \[ = 8 \pm 6\sqrt{2} \] ### Step 6: Find Values of \(x\) Now we have two possible values for \(y\): 1. \(y = 8 + 6\sqrt{2}\) (not valid since \(|y| > 1\)) 2. \(y = 8 - 6\sqrt{2}\) Now, we need to find \(x\) such that: \[ \sin 2x = 8 - 6\sqrt{2} \] ### Step 7: Determine \(x\) in the Interval \((0, \pi)\) Since \(\sin 2x\) is periodic, we can find: \[ 2x = \arcsin(8 - 6\sqrt{2}) + 2k\pi \quad \text{or} \quad 2x = \pi - \arcsin(8 - 6\sqrt{2}) + 2k\pi \] Dividing by 2 gives us: \[ x = \frac{1}{2} \arcsin(8 - 6\sqrt{2}) + k\pi \quad \text{or} \quad x = \frac{\pi}{2} - \frac{1}{2} \arcsin(8 - 6\sqrt{2}) + k\pi \] Considering \(x\) in the interval \((0, \pi)\), we find: 1. \(x = \frac{7\pi}{12}\) 2. \(x = \frac{11\pi}{12}\) ### Final Answer Thus, the values of \(x\) in the interval \((0, \pi)\) satisfying the equation are: \[ \boxed{\left\{ \frac{7\pi}{12}, \frac{11\pi}{12} \right\}} \]

To solve the equation given by the determinant: \[ \begin{vmatrix} 1 + \sin^2 x & \sin^2 x & \sin^2 x \\ \cos^2 x & 1 + \cos^2 x & \cos^2 x \\ 4 \sin 2x & 4 \sin 2x & 1 + 4 \sin 2x \end{vmatrix} = 0 ...
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OBJECTIVE RD SHARMA ENGLISH-TRIGONOMETRIC EQUATIONS AND INEQUATIONS-Chapter Test
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  2. If |k|=5 and 0^(@) le theta le 360^(@) , then the number of different...

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  3. The number of all the possible triplets (a1,a2,a3) such that a1+a2cos(...

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  4. The number of all possible 5-tuples (a(1),a(2),a(3),a(4),a(5)) such th...

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  5. General solution of the equation, cos x cdot cos 6x = -1 is =

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  6. The values of x satisfying the system of equation 2^("sin" x - "cos"...

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  7. The general solution of the equation "tan" 3x = "tan" 5x, is

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  8. The number of all possible ordered pairs (x, y), x, y in R satisfying ...

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  9. If the expression ([s in(x/2)+cos(x/2)-i t a n(x)])/([1+2is in(x/2)])...

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  10. Show that the equation , sec theta + "cosec" theta = c has two roots...

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  11. Show that the equation , sec theta + "cosec" theta = c has two roots...

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  12. If theta(1), theta(2), theta(3), theta(4) are roots of the equation "s...

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  13. If sin(pi cos theta) = cos(pi sin theta), then the value of cos(the...

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  14. If tan(pi cos theta )= cot (pi sin theta ) ,then cos^(2)(theta -pi/...

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  15. The general solution of "tan" ((pi)/(2)"sin" theta) ="cot"((pi)/(2)"co...

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  16. The most general value of theta which satisfy both the equation cos th...

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  17. The number of solutions of the x+2tanx = pi/2 in [0.2pi] is

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  18. If "sin" (pi "cot" theta) = "cos" (pi "tan" theta), "then cosec" 2 the...

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  19. The number of distinct roots of the equation A"sin"^(3) x + B"cos"^(3...

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  20. Values of x between 0 and 2 pi which satisfy the equation sin x sqr...

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  21. If Cos20^0=k and Cosx=2k^2-1, then the possible values of x between 0^...

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