Question 105
Let $ABC$ a triangle and $\Omega$ its circumscribed circle. We note $X$ the point of intersection of tangents at $\Omega$ in $B$ and $C$. We note $\varphi$ the angle $\widehat{B A X}$ and $\mu$ the angle $\widehat{X A C}$. We note $Y$ the point of the line $(A X)$ such as $\widehat{A C Y}=\varphi$. Show that $\widehat{A B Y}=\mu$.