MCQ
Let $P(\alpha,\beta)$ be a variable point which moves in $x-y$ plane such that $\frac{PA}{PB} = 2$ , where $A(1,0)$ and $B(0,-1)$. If $M$ and $m$ denote respectively the maximum and minimum value of $\alpha + \beta$, then value of $[\frac{M}{m}]$ is- (where [.] denotes the greatest integer function)
  • A
    $-1$
  • B
    $-3$
  • $0$
  • D
    $1$

Answer

Correct option: C.
$0$
c
Locus of $P \Rightarrow \frac{P A}{P B}=2$

$\sqrt{\frac{(x-1)^{2}+y^{2}}{x^{2}+(y+1)^{2}}}=2$

$x^{2}+y^{2}+\frac{2}{3} x+\frac{8}{3} y+1=0,$ centre $\equiv\left(-\frac{1}{3},-\frac{4}{3}\right)$

radius $=\frac{2 \sqrt{2}}{3}$

Co-ordinates of

$P(\alpha, \beta) \equiv\left(-\frac{1}{3}+\frac{2 \sqrt{2}}{3} \cos \theta,-\frac{4}{3}+\frac{2 \sqrt{2}}{3} \sin \theta\right)$

$(\alpha+\beta)=-\frac{5}{3}+\frac{2 \sqrt{2}}{3}(\cos \theta+\sin \theta)$

$\left[\frac{(\alpha+\beta)_{\max }}{(\alpha+\beta)_{\min }}\right]=\left[\frac{-\frac{1}{3}}{-3}\right]=0$

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