Mathematics - Straight Lines Question with Solution | TestHub

Take the reflection of $△ABC$ in $\mathrm{BC}.\mathrm{PM}={\mathrm{PM}}^{\prime }.\mathrm{PA}+\mathrm{PM}=\mathrm{PA}+{\mathrm{PM}}^{\prime }$; it is minimum when M'PA lies in a line. Now apply cosine rule in triangle ABM'. We will get ${\mathrm{AM}}^{\prime }=10\sqrt{7}$.