It is given that $\overline{AB}\cong \overline{AC}$, thus $\mathrm{\angle }B=\mathrm{\angle }C$.

Because $\mathrm{\angle }A+\mathrm{\angle }B+\mathrm{\angle }C={180}^{\circ };\mathrm{\angle }A={48}^{\circ }$, we have: $\mathrm{\angle }C=\frac{{180}^{\circ }-{48}^{\circ }}{2}={66}^{\circ }$