Find the equations of the bisectors of the angles between the coordinate axes.
Find the equations of the bisectors of the angles between the coordinate axes.

There are two bisectors of the coordinate axes.

Their inclinations with the positive x-axis are

    \[{{45}^{o}}~and\text{ }{{135}^{o}}\]

The slope of the bisector is

    \[m\text{ }=\text{ }tan\text{ }{{45}^{o}}~or\text{ }m\text{ }=\text{ }tan\text{ }{{135}^{o}}\]

i.e.,

    \[m\text{ }=\text{ }1\text{ }or\text{ }m\text{ }=\text{ }-1,\text{ }c\text{ }=\text{ }0\]

By using the formula,

    \[y\text{ }=\text{ }mx\text{ }+\text{ }c\]

Now, substitute the values of

    \[m\text{ }and\text{ }c\]

we get

    \[y\text{ }=\text{ }x\text{ }+\text{ }0\]

    \[x\text{ }\text{ }y\text{ }=\text{ }0\text{ }or\text{ }y\text{ }=\text{ }-x\text{ }+\text{ }0\]

    \[x\text{ }+\text{ }y\text{ }=\text{ }0\]

∴ The equation of the bisector is

    \[x~\pm ~y\text{ }=\text{ }0\]