8.  Fig. depicts a racing track whose left and right ends are semicircular.


The distance between the two inner parallel line segments is 60 m and they are each 106 m long. If the track is 10 m wide, find :

  (i) the distance around the track along its inner edge

Answers (1)
D Devendra Khairwa

The distance around the track is Length of two straight lines +  Length of two arcs.

Length of the arc is  - 

                                  =\ \frac{1}{2}\times 2\pi r

                                 =\ \frac{1}{2}\times 2\pi \times 30\ =\ 30\pi\ m

Thus the length of the inner track is :      

                                                      =\ 106\ +\ 30\pi\ +\ 106\ +\ 30\pi

                                                     =\ 212\ +\ 60\pi

                                                    =\ \frac{2804}{7}\ m