Answer
544 ft
Work Step by Step
The length of the guy wire is the hypotenuse,
the height of the tower (x) is the leg opposite to $65^{o}.$
$\displaystyle \sin 65^{o}=\frac{x}{600}$
$ x=600\sin 65^{o}\approx$543.784672222$\approx$ 544 ft