Step-by-step explanation:
The pendulum swings over an angle of 2×(2°30') or 5° so we need to convert this to radian measure first:
[tex]5° × \left(\dfrac{\pi}{180°}\right) = 0.0873\:\text{rad}[/tex]
so the arc length is given by
[tex]s = r\theta = (50\:\text{cm})(0.0873\:\text{rad}) = 4.36\:\text{cm}[/tex]
