(a) In Fig.-2, if a circle touches the side $\mathrm{QR}$ of $△\mathrm{PQR}$ at $\mathrm{S}$ and extended sides $\mathit{P}\mathit{Q}$ and $\mathit{P}\mathit{R}$ at $\mathit{M}$ and $\mathit{N}$, respectively, then
OR
(b) In Fig. 3, a triangle $\mathrm{ABC}$ is drawn to circumscribe a circle of radius 4 $\mathrm{cm}$ such that the segments $\mathrm{BD}$ and $\mathrm{DC}$ into which $\mathrm{BC}$ is divided by the point of contact $\mathrm{D}$ are of lengths $6\mathrm{cm}$ and $8\mathrm{cm}$ respectively. If the area of $△\mathrm{ABC}$ is $84{\mathrm{cm}}^2$, find the lengths of sides $\mathrm{AB}$ and $\mathrm{AC}$.