Note that\(BE = B'E = 12\)
By the Pythagorean Theorem, \(AB' = \sqrt{B'E^2 - AE^2} = \sqrt{144 - 64} = \sqrt{80} = 4 \sqrt 5\)
Also, note that by the Pythagorean Theorem, \(B'F = DF^2 + B'D^2 = CF^2 + BC^2\)
SImplifying the equation gives us: \(4 + BC^2 = 324 + B'D^2\)
But, note that \({B'D} = {BC - AB'} = BC - 4 \sqrt 5\)
This means that our equation simplifies to \(4 + BC^2 = 324 + (BC - 4 \sqrt5)^2\)
Now, just solve for \(BC\), and I assume you can take it from here?