Find the value of c using the give chord and secant lengths

Given the figure of a circle
We will find the value of c using the given chord and secant lengths as follows:
[tex]10*(10+18)=12*(12+c)[/tex]Solve the equation to find the value of c
[tex]\begin{gathered} 10*28=12*(12+c) \\ 12+c=\frac{10*28}{12} \\ c=\frac{280}{12}-12=11.33 \end{gathered}[/tex]Rounding to the nearest tenth
So, the answer will be c = 11.3