\problemdef{Geometry}{1}{ \statement{ What is the largest number of obtuse angles that nine rays emanating from one point can form on a plane? } \answer{27} } \problemdef{Geometry}{2}{ \statement{ The three sides of the trapezoid are equal, and one of the angles is $40^\circ$ larger than the other. Find an acute angle between the diagonals of the trapezoid. } \answer{$70^\circ$} } \problemdef{Geometry}{3}{ \statement{ In a cyclic quadrilateral $ABCD$ angle $ABD$ is $30^\circ$ and angle $BCA$ is $42^\circ$. Find angle $DAB$. } \answer{$108^\circ$} } \problemdef{Geometry}{4}{ \statement{ In a triangle $ABC$, angle $B$ is $20^\circ$, and angle $C$ is $40^\circ$. The bisector $AD$ of angle $A$ is 12. Find the difference between the sides $BC$ and $AB$. } \answer{12} }