The inside perimeter of a running track (shown in Fig. 20.24) is 400 m. The length of each of the straight portion is 90 m and the ends are semi-circles. If track is everywhere 14 m wide, find the area of the track. Also, find the length of the outer running track.
Perimeter of the inner track = 2× Length of rectangle + perimeter of two semi-circular ends
Perimeter of the inner track = length + length + 2πr
Hence, the radius of inner circle = 35 m
Radius of outer track = radius of inner track + width of the track
Radius of outer track = 35 + 14 = 49m
Length of outer track = 2× Length of rectangle + perimeter of two outer semi-circular ends
Length of outer track = 2× 90 + 2πr
Length of outer track = 
Length of outer track = 
Area of inner track = area of inner rectangle + area of two inner semi-circles
Area of inner track = length× breadth + πr2
Area of inner track = 
Area of inner track = 6300 + 3850
Area of inner track = 10150 m2
Area of outer track = area of outer rectangle + area of two outer semi-circles
Breadth of outer track = 35 + 35 +14 + 14 = 98 m
Area of outer track = length× breadth + πr2
Area of outer track = 
Area of outer track = 8820 + 7546
Area of outer track = 16366 m2
Area of path = area of outer track – area of inner track
Area of path = 16366 – 10150 = 6216 m2