Question
P is a point equidistant from two lines l and m intersecting at a point A (see figure). Show that $AP$ bisects the angle between them.

Answer


Given: $P$ is a point equidistant from two lines $I$ and $m$ intersect at a point $A$.
To Prove: AP bisects the angle between them. i.e. $\angle \mathrm{PAB}=\angle \mathrm{PAC}$
Proof: Let $P B$ and $P C$ be perpendiculars from $P$ on lines $I$ and $m$ respectively. Since $P$ is equidistant from lines $I$ and $m$.
Therefore, $P B=P C$
In $\triangle P A B$ and $\triangle P A C$, we have
$\mathrm{PB}=\mathrm{PC} \text { [Given] }$
$\angle \mathrm{PBA}=\angle \mathrm{PCA}\left[\text { Each equal to } 90^{\circ}\right. \text { ] }$
$\text { and, } \mathrm{PA}=\mathrm{PA}[\mathrm{Common}]$
$\triangle \mathrm{PAB} \cong \triangle \mathrm{PAC}[\mathrm{By} \mathrm{~RHS} \text { congruence criterion] }$
$\Rightarrow \angle \mathrm{PAB}=\angle \mathrm{PAC}$
Hence Proved

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free