Question 157
Draw a semicircle with center in $O$ and diameter $A B$ and, inside, another, with diameter $O A$. trace through a point $C$ of $O A$ a line perpendicular to said radius $O A$, which will cut to the small semicircle in $D$ and the big one $E$ And finally the straight $A D$ that will cut the large semicircle in $F$. Show that the circle circumscribed to the triangle $D E F$ It is tangent to the rope $A E$ on $E$