ANSWER
[tex]x = 11.5[/tex]
EXPLANATION
Triangle ABC is a right angle triangle.
We can apply the Pythagorean Theorem to get,
[tex] {x}^{2} + {8}^{2} = {14}^{2} [/tex]
We now solve for x to get,
[tex] {x}^{2} = {14}^{2} - {8}^{2}[/tex]
The right hand side is difference of two squares, this factors to give us,
[tex] {x}^{2} = (14 - 8)(14 + 8)[/tex]
[tex] {x}^{2} = 6 \times 22[/tex]
[tex] {x}^{2} = 132[/tex]
We take the positive square root of both sides to obtain,
[tex]x = \sqrt{132} [/tex]
[tex]x = 11.48[/tex]
[tex]x = 11.5[/tex]