Given In `DeltaABC, BM bot AC and CN bot AB`.
To prove Points B, C, M and N are con-cyclic.
Construction Draw a circle passing through the points B, C, M and N.
Proof Suppose, we consider BC as a diameter of the circle. Also, we know that BC subtends a `90^(@)` to the circle.
So, the points M and N should be on a circle.
Hence, BCMN form a con-cyclic quadrilateral.