13. Five marks exercise problems VIII

Two line segments \(\overline{AD}\) and \(\overline{BC}\) intersect at \(O\). Joining \(\overline{AB}\) and \(\overline{DC}\) we get two triangles, \(\Delta AOB\) and \(\Delta DOC\) as shown in the figure. Find the \(\angle A\) and \(\angle B\).

 

 

\(A = \) \(^\circ\)

 

\(B = \) \(^\circ\)