ANSWER
[tex]x = 22 \: \: units[/tex]
EXPLANATION
The line from the center of the circle to the upper chord meets it at right angles, this means that, this line bisects the upper chord.
Hence the length of the upper chord is 2(11)=22 units.
Since the distance from the upper chord to the center is 12 units and the distance from the lower chord to the center is also 12 units, the two chords must be equal.
[tex] \therefore \: x = 22 \: units[/tex]
