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 $AB$.