
$\begin{aligned}
& \mathrm{m}_{\mathrm{PR}}=2-\sqrt{3}=\tan 15^{\circ} \
& \therefore \frac{\alpha}{2}=15^{\circ} \quad \Rightarrow \alpha=30^{\circ}
\end{aligned}$
equation of PR :
$\begin{aligned}
& y=\tan 15^{\circ}(x-a) \
& y=(2-\sqrt{3})(x-a)
\end{aligned}$
⊥ distance from origin =21
4+3−43+13a−2a=212(2−3)∣a∣(2−3)=21∣a∣=2−32=2(2+3)a2=2(2+3)3a2tan2α−233×(4+23)⋅31−23=4