\(ABCD\) is a trapezium. Here, the sides \(AB\) and \(CD\) are parallel to each other. Also, the diagonals intersect at \(O\). Prove that \(\frac{AO}{BO} = \frac{CO}{DO}\).
 
Let us look at the figure given below for a better understanding.
 
21 Ресурс 1.svg
 
In \(\triangle ABC\) and \(\triangle COD\), .
 
This makes, \(\angle OAB\) \(=\) and \(\angle ODC\)
 
Since
 
By  similarity criterion, we have, "If two angles of one triangle are respectively equal to two angles of another triangle, then the two triangles are similar."
 
Thus, \(\triangle AOB \sim\) .
 
Also, \(\frac{AO}{CO} =\) .
 
\(\frac{AO}{BO} =\)
 
Hence proved.