Calculation formula of arc length Just answer the formula

Calculation formula of arc length Just answer the formula

L = 2 π R n / 360 ° = π R n / 180 ° (r = radius * n = absolute value of arc angle)

A formula for finding the length of circular arc

L=nπ r/180

1. The total length of a standard runway is 400 meters, the inner radius of the curve is 36 meters, and each runway is 1.2 meters wide
(1) If a 400 meter race is to be conducted, how many meters should the starting line of the third runner be earlier than that of the first runner?
(2) If an 800 meter race is to be conducted, each runner must complete the whole race on his own track. In this way, how many meters should the starting line of the eighth runner be earlier than that of the first runner?

(1) If you run through a full circle, the radius of the third curve is 2.4 meters larger than that of the first curve, you need to go ahead of time
2 π r = 3.14 × 2.4 × 2 = 15.072 (m)
(2) The radius of the 8th curve is 7 * 1.2 = 8.4m larger than that of the first curve, which needs to be 3.14 × 8.4 × 2 = 52.752m earlier

The inner circle of the school sports ground is 400 meters long, the curve is semicircular, and the runway is 1.1 meters wide. Two students run one circle along the inner and outer runways respectively. How many meters more do the students run on the outer runways? (the number is reserved for two) please,

In your question, the school playground can be illustrated as shown in the figure. The inner circle is 400m long, the curve is semicircle, the radius is r, and the outer circle is r, R = R + 1.1m. The length of inner ring can be written as 2 open R + 2L. Where l is the length of straight track. The length of outer ring can be written as 2 open R + 2L = 2 open (R + 1.1) + 2L. Outer ring inner ring = 2 open (R + 1.1) + 2L - (2 open R + 2L) = 2.2 open = 6.91m