It is given AB = CD.
So, OF = OE = 8 cm [Equal chords are equidistant from centre] ...... (1)
In ΔOEB
OB = 20 cm [Radius]
OE = OF = 16 cm [from (1)]
Since a line through the center that bisects the chord is perpendicular to the chord, we must have ∠OBE=90∘
∴OB2=OE2+EB2
[∵∠OEB is 90∘]
EB2=OB2−OE2
EB2=(20)2−(16)2=144
EB = 12 cm