Question

The distance between the pair of lines represented by $x^2+2\sqrt{2}xy+2y^2+4x+4\sqrt{2}y+1=0$, is

• A. 1
• B. 2
• C. $\sqrt{2}$
• D. 4

Answer 1

Answer: (B)

Given,
$x^2+2\sqrt{2}xy+2y^2+4x+4\sqrt{2}y+1=0$
We know that,
The distance ' $d$ ' between the pair of straight lines represented by
$a{x}^2+2hxy+b{y}^2+2gx+2fy+c=0$ is given by
$d=2\sqrt{\frac{g^2-ac}{a(a+b)}}$
Here, $a=1,b=2,c=1,g=2$
$\therefore d=2\sqrt{\frac{4-1}{1(1+2)}}=2\sqrt{\frac{3}{3}}=2$