In the adjoining figure, 
is a square. A circle drawn with center 
cuts the suare in 
and 
Prove that 
In triangle OPX and triangle ORY,
OX = OY [Radius]
∠OPX = ∠ORY [Common]
OP = OR [Sides of square]
By side-angle-side criterion of congruence,
ΔOPX ≅ ΔORY
∴ PX = RY
⇒ PQ – PX = QR – RY [PQ = QR]
⇒ QX = QY Proved.
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