In AABC, AB = AC and ZBAC 30°. What is the value of ZABC?

Solve: given that, $\triangle \mathrm{ABC} \rightarrow \mathrm{AB}=\mathrm{BC} \& \triangle B A C=30^{\circ}$ We know that, the sum of the three angle of a triangle is $180^{\circ} \therefore\left(180^{\circ}-30^{\circ}\right)=150^{\circ}$ $\therefore \angle \mathrm{ABC}=\frac{150^{\circ}}{2}=75^{\circ}$