If radius = 30, the circumference = 2*PI *radius =
<span>
<span>
<span>
188.4955592154
</span>
</span>
</span>
cm The arc = 18*PI cm =
<span>
<span>
<span>
56.5486677646
</span>
</span>
</span>
The arc is (<span>
56.5486677646 / </span><span><span>188.4955592154) = one third of the </span></span><span><span> </span></span><span><span>circumference and so it subtends a central angle of 120 degrees. </span></span><span><span> </span></span><span><span> </span></span>
