Length of inner curved portion
= [340 - (2 × 60) m
= (340 - 120) m = 220 m
Therefore, the length of each inner curved surface = 110 m.
Let radius be r, then
πr = 110 m
⇒r = 35 m
So, inner radius (OB = O'C)
= 35 m
and outer radius (OA = O'D) = (55 + 7)
= 42 m.
Hence, reqd. Area = (Area of 2 rectangles) + (Area of the circular rings)
And, length of the outer boundary of the park
A wheel of diameter 42 cm makes 240 rounds per minute. Find
(i) The total distance covered by the wheel in one minute.
(ii) The speed of the wheel in km/hr.)