Length of an Arc

This item is taken from IGCSE Mathematics (0580) Paper 43 (Extended) of June 2013.

To deal with this item, let us summarize the details of the problem:
   (a) Syllabus area: Trigonometry
   (b) Specific topic: Length of an Arc
   (c) Formula Needed: 

It is given that the central angle subtended by the arc (fence) measures 210 degrees. The illustration/photo below shows the sector enclosed by the fence and the central angle.

Using the values given,

Therefore, the length of the fence is 165 m.

---------------------------------------------------------------------------------------------------------------
Your comments and suggestions are welcome here. Write them in the comment box below. 

Thank you and God bless!