In the figure, there is a jogging track that has to be renovated. The cost of renovation is Rs. 15 per square meters. For the circular parts, the inner and outer radii are 6 m and 8 m respectively. Find the area highlighted in green colour (in square meters).
88
There are two semi-circular parts (green parts) which add up to be a complete circle.
So, area of the circular part of the track = π[(outer radius)2−(inner radius)2]
=π(82−62)=227×14×2=88m2
(Using identity a2–b2 = (a + b)(a - b))