Question 47
Let $c(O, R)$ be a circle, $AB$ a diameter and $C$ an arbitrary point different than $A$ and $B$ such that $AOC \gt 90^\circ$. On the radius $OC$ we consider point $K$ and the circle $c_1(K, KC)$. The extension of the segment $KB$ meets the circle ($c$) at point $E$. From $E$ we consider the tangents $ES$ and $ET$ to the circle ($c_1$). Prove that the lines $BE, ST$ and $AC$ are concurrent.