Answer:
radius ≈ 10.77 cm
Step-by-step explanation:
The segment from the centre O to the chord is a perpendicular bisector.
Thus 2 right triangles are formed with legs 10 cm and 4 cm ( half of XY )
The radius r is the hypotenuse.
Using Pythagoras' identity, then
r² = 4² + 10² = 16 + 100 = 116 ( take the square root of both sides )
r = ≈ 10.77 cm ( to 2 dec. places )