If the length of a focal chord drawn to the parabola
\[
y^2=64x
\]
is \(289\) and the angle made by this focal chord with the positive \(X\)-axis measured in the positive direction is an acute angle, then the slope of the focal chord is
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For the parabola
\[
y^2=4ax,
\]
the length of a focal chord with parameter \(m\) is
\[
\boxed{a\left(m+\frac1m\right)^2.}
\]