[tex]\displaystyle AB=AC=4 \\ m(\sphericalangle A)=30^{\circ} \\ AB=c=4 \\ AC=b=4\\ c=b=4 \\ A_{\triangle ABC}= \frac{b \cdot c \cdot sin~A}{2} = \frac{4 \cdot 4 \cdot sin~30^{\circ}}{2} = \frac{\not4 \cdot \not4 \cdot \frac{1}{\not2} }{ \not2} = 2 \cdot 2 =4 [/tex]
