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QJEEM22Ma06e3: JEE Main 2022 Mathematics - Class 11 JEEM22Ma06e3 Solution: Let 1 , 2 ( 1 < 2 ) be the values of fo the points ( , 3), (2,…

Let α\alpha 1, α\alpha 2 ( α\alpha 1 < α\alpha 2) be the values of α\alpha fo the points ( α\alpha , −- 3), (2, 0) and (1, α\alpha ) to be collinear. Then the equation of the line, passing through ( α\alpha 1, α\alpha 2) and making an angle of π3{\pi \over 3} with the positive direction of the x-axis, is :

Multiple Choice Options

  • A x−3y−33+1=0x - \sqrt 3 y - 3\sqrt 3 + 1 = 0
  • B 3x−y+3+3=0\sqrt 3 x - y + \sqrt 3 + 3 = 0
  • C x−3y+33+1=0x - \sqrt 3 y + 3\sqrt 3 + 1 = 0
  • D 3x−y+3−3=0\sqrt 3 x - y + \sqrt 3 - 3 = 0

Step-by-Step Verified Solution

Points A( α\alpha , −- 3), B(2, 0) and C(1, α\alpha ) are collinear.

JEE Main 2022 (Online) 30th June Morning Shift Mathematics - Straight Lines and Pair of Straight Lines Question 55 English Explanation

∴\therefore Slope of AB = Slope of BC

⇒0+32−α=α−01−2\Rightarrow {{0 + 3} \over {2 - \alpha }} = {{\alpha - 0} \over {1 - 2}}

⇒−3=α(2−α)\Rightarrow - 3 = \alpha (2 - \alpha )

⇒−3=2α−α2\Rightarrow - 3 = 2\alpha - {\alpha ^2}

⇒α2−2α−3=0\Rightarrow {\alpha ^2} - 2\alpha - 3 = 0

⇒α2−3α+α−3=0\Rightarrow {\alpha ^2} - 3\alpha + \alpha - 3 = 0

⇒α(α−3)+1(α−3)=0\Rightarrow \alpha (\alpha - 3) + 1(\alpha - 3) = 0

⇒(α+1)(α−3)=0\Rightarrow (\alpha + 1)(\alpha - 3) = 0

⇒α=−1, 3\Rightarrow \alpha = - 1,\,3

Given, {\alpha _1} &lt; {\alpha _2}

∴\therefore α1=−1{\alpha _1} = -1 and α2=3{\alpha _2} = 3

∴\therefore (α1, α2)=(−1, 3)\left( {{\alpha _1},\,{\alpha _2}} \right) = ( - 1,\,3)

Now, equation of the line passing through ( −- 1, 3) and making angle π3{\pi \over 3} with positive x-axis is

(y−y1)=m(x−x1)(y - {y_1}) = m(x - {x_1})

⇒y−3=(tan⁡π3)(x+1)\Rightarrow y - 3 = \left( {\tan {\pi \over 3}} \right)(x + 1)

⇒y−3=3(x+1)\Rightarrow y - 3 = \sqrt 3 (x + 1)

⇒3x−y+3+3=0\Rightarrow \sqrt 3 x - y + \sqrt 3 + 3 = 0

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