Straight Line Question 107

Question: The distance of the lines $ 2x-3y=4 $ from the point (1, 1) measured parallel to the line $ x+y=1 $ is[Orissa JEE 2002]

Options:

A) $ \sqrt{2} $

B) $ \frac{5}{\sqrt{2}} $

C) $ \frac{1}{\sqrt{2}} $

D)6

Show Answer

Answer:

Correct Answer: A

Solution:

  • The slope of line $ x+y=1 $ is $ -1 $ \ It makes an angle of $ 135{}^\circ $ with x-axis. The equation of line passing through $ (1,1) $ and making an angle of $ 135{}^\circ $ is, $ \frac{x-1}{\cos 135^{o}}=\frac{y-1}{\sin 135^{o}}=r $
    Þ $ \frac{x-1}{-1/\sqrt{2}}=\frac{y-1}{1/\sqrt{2}}=r $ Co-ordinates of any point on this line are $ ( 1-\frac{r}{\sqrt{2}},1+\frac{r}{\sqrt{2}} ) $ If this point lies on $ 2x-3y=4 $ , then $ 2( 1-\frac{r}{\sqrt{2}} )-3( 1+\frac{r}{\sqrt{2}} )=4 $ Þ $ r=\sqrt{2}. $