2.3. A circle $k$ is circumscribed around an isosceles triangle $ABC (AB = AC)$. The line $l$ contains the vertex $A$ and intersects the segment $BC$ at point $D$, and the circle $k$ at point $E$. If $AB = c$ and $AE = m$, determine the length of the segment $AD$.
2.3. Triangle $A B E$ is similar to triangle $A D B$, so $\frac{|A B|}{|A E|}=\frac{|A D|}{|A B|} \cdot$ Therefore, $|A D|=\frac{c^{2}}{m}$.