In trapezium ABCD, diagonals AC and BD are drawn, which meet at point O. Prove that triangle COB

In trapezium ABCD, diagonals AC and BD are drawn, which meet at point O. Prove that triangle COB is similar to triangle AOD.

Since ABCD is a trapezoid, its bases are parallel, АD || BC.

In the triangles COB and AOD, the angle OBC = ODA as criss-crossing angles at the intersection of parallel straight lines ВС and АD of the secant ВD.

Angle BOC = AOD as vertical angles at the intersection of diagonals AC and BD.

Then the triangles COB and AOD are similar in two angles, as required.



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