Cyclic Quadrilaterals are often important objects in a Geometry problem. Recognizing them can lead to a path to the solution. A case in point is this problem from Pre RMO 2017.
How to recognize cyclic quadrilaterals?
- Opposite angles add up to \( \pi \)
- Two angles subtended by one segment are equal
- Sum of the product of opposite sides equal product of diagonals
Now look into this problem: