Question

The equation of the bisector of the acute angle between the lines $2x-y+4=0$ and $x-2y=1$ is

• A. $x+y+5=0$
• B. $x-y+1=0$
• C. $x-y=5$
• D. none of these

Answer 1

Answer: (B)

Clearly, from the figure, the origin is contained in the acute angle. Writing the equations of the lines as
$2x-y+4=0$ and $-x+2y+1=0$,
the required bisector is
$\frac{2x-y+4}{\sqrt{5}}=\frac{-x+2y+1}{\sqrt{5}}$