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9.Straight Line
hard
Let two points be $\mathrm{A}(1,-1)$ and $\mathrm{B}(0,2) .$ If a point $\mathrm{P}\left(\mathrm{x}^{\prime}, \mathrm{y}^{\prime}\right)$ be such that the area of $\Delta \mathrm{PAB}=5\; \mathrm{sq}$ units and it lies on the line, $3 x+y-4 \lambda=0$ then a value of $\lambda$ is
A
$1$
B
$4$
C
$3$
D
$-3$
(JEE MAIN-2020)
Solution

$\overline{A B}: 3 x+y-2=0$
Also, $\frac{1}{2} \times \sqrt{10} \times h=5$
$\Rightarrow h=\sqrt{10}$
$\Rightarrow \frac{|4 \lambda-2|}{\sqrt{10}}=\sqrt{10} \Rightarrow \lambda=3,-2$
Standard 11
Mathematics