Answer
$s = r\theta = (8.0 \text{m})(120^\circ) \left( \frac{2\pi , \text{rad}}{360^\circ} \right) = 17 \text{m}$
Work Step by Step
the carnival swing is sweeping out an arc radius which you find with:
$s = r\theta \left( \frac{2\pi , \text{rad}}{360^\circ} \right)$
