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JEE Main 20238 AprilEvening Shift
Exam
JEE Main
Year
2023
Date
8 April
Shift
Evening Shift
Subject
Mathematics
Chapter
Circle

JEE Main 2023 · 8 April · Evening Shift · Mathematics · Circle

Let O be the origin and OP and OQ be the tangents to the circle x ^...

Let OO be the origin and OPandOQOP and OQ be the tangents to the circle x2+y2−6x+4y+8=0{x}^{2} + {y}^{2} - 6x + 4y + 8 = 0 at the points PandQP and Q on it. If the circumcircle of the triangle OPQOPQ passes through the point \left(\alpha, \dfrac{1}{2}\right),thenavalueof, then a value of\alpha$ isLet O be the origin and OP and OQ be the tangents to the circle x ^ 2 + y ^ 2 - 6x + 4y + 8 = 0 at the points P and Q

Options

  1. A32\dfrac{3}{2}
  2. B−12- \dfrac{1}{2}
  3. C52\dfrac{5}{2}
  4. D11

Correct answer

C. 52\dfrac{5}{2}

Step-by-step solution

The given information can be represented in the form of the diagram below.Let O be the origin and OP and OQ be the tangents to the circle x ^ 2 + y ^ 2 - 6x + 4y + 8 = 0 at the points P and Q

Since angle in a semicircle is a right angle.

Hence, the other circle will be passing through the centre of the first circle.

The two ends of diameter of the circle is O(0,0)andC(3,−2).</p><p>Hence,O\left(0, 0\right)\text{and}C\left(3, - 2\right).</p><p>Hence, the requiredequationofcircleis(x−0)required equation of circle is \left(x - 0\right)\left(x - 3\right) + \left(y - 0\right) \left(y - \left(- 2\right)\right) = 0</p><p></p><p>⇒ {x}^{2} + {y}^{2} - 3x + 2y = 0</p><p>Put(α,12)</p><p>Put \left(\alpha, \dfrac{1}{2}\right) in the above equation⇒α2+14−3α+1=0⇒ {\alpha}^{2} + \dfrac{1}{4} -3\alpha + 1 = 0
⇒α2−3α+54=0⇒ {\alpha}^{2} - 3\alpha + \dfrac{5}{4} =0
⇒4α2−12α+5=0⇒ 4{\alpha}^{2} - 12\alpha + 5 = 0

⇒4α2−10α−2α+5=0⇒ 4{\alpha}^{2} - 10\alpha - 2\alpha + 5 = 0

⇒2α(2α−5)−1(2α−5)=0⇒α=12,52⇒ 2\alpha ( 2\alpha - 5 ) - 1 ( 2\alpha - 5 ) = 0⇒ \alpha = \dfrac{1}{2}, \dfrac{5}{2}

Therefore this isthecorrectoption.the correct option.

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