Consider $L_1: 2 x+3 y+p-3=0 ; L_2: 2 x+3 y+p+3=0$ where $p$ is a real number and $C: x^2+y^2+6 x-10 y+30=0$…

Consider $L_1: 2 x+3 y+p-3=0 ; L_2: 2 x+3 y+p+3=0$ where $p$ is a real number and $C: x^2+y^2+6 x-10 y+30=0$.
Statement 1 If line $L_1$ is a chord of circle $C$, then line $L_2$ is not always a diameter of circle $C$.
Statement 2 If line $L_1$ is a diameter of circle $C$, then line $L_2$ is not a chord of circle $C$.
  1. Statement 1 is true, Statement 2 is true, Statement 2 is a correct explanation for Statement 1.
  2. Statement 1 is true, Statement 2 is true, Statement 2 is not a correct explanation for Statement 1.
  3. Statement 1 is true, Statement 2 is false.
  4. Statement 1 is false, Statement 2 is true

Solution

Equation of circle $C$ is $ \begin{aligned} (x+3)^2+(y-5)^2 & =9+25-30=4 \\ \Rightarrow \quad \quad(x+3)^2+(y-5)^2 & =2^2 \\ \text { Centre } & =(3,-5) \end{aligned} $ If $L_1$ is diameter, then $2(3)+3(-5)+p-3=0 \Rightarrow p=12$ $\therefore \quad L_1$ is $2 x+3 y+9=0$ and $L_2$ is $2 x+3 y+15=0$ Distance of centre of circle from $L_2=\left|\frac{2(3)+3(-5)+15}{\sqrt{2^2+3^2}}\right|=\frac{6}{\sqrt{13}} < 2 \quad$ [radius of circle] $\therefore L_2$ is a chord of circle $C$. Statement 2 is false

Asked in: JEE Advanced 2008 (Paper 2)

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