ANSWER
[tex]x = 4.1[/tex]
EXPLANATION
The line segment connecting the center and the chord bisects the chord.
Half of the length of this chord forms one of the shorter legs of the right triangle.
[tex] = \frac{15.6}{2} = 7.8[/tex]
We use the Pythagoras Theorem to obtain;
[tex] {x}^{2} + {7.8}^{2} = {8.8}^{2} [/tex]
[tex] {x}^{2} = {8.8}^{2} - {7.8}^{2} [/tex]
[tex] {x}^{2} = 16.6[/tex]
[tex]x = \sqrt{16.6} [/tex]
[tex]x = 4.1[/tex]