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Consider the equation 5 sin^2 x + 3 sin ...

Consider the equation `5 sin^2 x + 3 sin x cos x - 3 cos^2 x =2 `.......... (i)
`sin^2 x - cos 2 x =2-sin 2 x `........... (ii)
If ` alpha ` is a root (i) and ` beta` is a root of (ii), then ` tan alpha + tan beta ` can be equal to

A

`(1+sqrt(69)//6`

B

`-1-sqrt(69)//6`

C

`(-3 +sqrt(69))/(6)`

D

`(3-sqrt(69))/(3)`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the given equations and find the value of \( \tan \alpha + \tan \beta \), let's break down the problem step by step. ### Step 1: Solve the first equation The first equation is: \[ 5 \sin^2 x + 3 \sin x \cos x - 3 \cos^2 x = 2 \] Rearranging gives: \[ 5 \sin^2 x + 3 \sin x \cos x - 3 \cos^2 x - 2 = 0 \] Next, we divide the entire equation by \( \cos^2 x \): \[ 5 \tan^2 x + 3 \tan x - 3 - \frac{2}{\cos^2 x} = 0 \] Using the identity \( \sec^2 x = 1 + \tan^2 x \), we can substitute \( \frac{2}{\cos^2 x} \) with \( 2 \sec^2 x \): \[ 5 \tan^2 x + 3 \tan x - 3 - 2(1 + \tan^2 x) = 0 \] This simplifies to: \[ (5 - 2) \tan^2 x + 3 \tan x - 5 = 0 \] \[ 3 \tan^2 x + 3 \tan x - 5 = 0 \] ### Step 2: Solve the quadratic equation Now we can solve the quadratic equation: \[ 3 \tan^2 x + 3 \tan x - 5 = 0 \] Using the quadratic formula \( \tan x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \): - Here, \( a = 3 \), \( b = 3 \), and \( c = -5 \). Calculating the discriminant: \[ D = b^2 - 4ac = 3^2 - 4 \cdot 3 \cdot (-5) = 9 + 60 = 69 \] Now substituting into the formula: \[ \tan x = \frac{-3 \pm \sqrt{69}}{6} \] This gives us two potential values for \( \tan \alpha \): \[ \tan \alpha = \frac{-3 + \sqrt{69}}{6} \quad \text{or} \quad \tan \alpha = \frac{-3 - \sqrt{69}}{6} \] ### Step 3: Solve the second equation The second equation is: \[ \sin^2 x - \cos 2x = 2 - \sin 2x \] Using the identities \( \cos 2x = \cos^2 x - \sin^2 x \) and \( \sin 2x = 2 \sin x \cos x \): \[ \sin^2 x - (\cos^2 x - \sin^2 x) = 2 - 2 \sin x \cos x \] \[ \sin^2 x + \sin^2 x - \cos^2 x = 2 - 2 \sin x \cos x \] \[ 2 \sin^2 x - \cos^2 x = 2 - 2 \sin x \cos x \] Dividing by \( \cos^2 x \): \[ 2 \tan^2 x - 1 = 2 \sec^2 x - 2 \tan x \] Substituting \( \sec^2 x = 1 + \tan^2 x \): \[ 2 \tan^2 x - 1 = 2(1 + \tan^2 x) - 2 \tan x \] \[ 2 \tan^2 x - 1 = 2 + 2 \tan^2 x - 2 \tan x \] Rearranging gives: \[ -1 + 2 = 2 \tan x \quad \Rightarrow \quad 1 = 2 \tan x \quad \Rightarrow \quad \tan x = \frac{1}{2} \] Thus, we have: \[ \tan \beta = \frac{3}{2} \] ### Step 4: Find \( \tan \alpha + \tan \beta \) Now we can find \( \tan \alpha + \tan \beta \): \[ \tan \alpha + \tan \beta = \left(\frac{-3 + \sqrt{69}}{6}\right) + \frac{3}{2} \] Converting \( \frac{3}{2} \) to have a common denominator of 6: \[ \tan \alpha + \tan \beta = \frac{-3 + \sqrt{69}}{6} + \frac{9}{6} = \frac{-3 + \sqrt{69} + 9}{6} = \frac{6 + \sqrt{69}}{6} \] Thus, the final result is: \[ \tan \alpha + \tan \beta = 1 + \frac{\sqrt{69}}{6} \]
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