Respuesta :
Solution
The two straightaway sections of the track are each 84.39 meters. The two semi-circular sections can be joined to form a circle whose radius is 36.5 meters and so the diameter of this circle is 2×36.5=73 meters. The circumference of this circle will be π×73 meters and so the total perimeter of the track is
2×84.39+π×73≈398.12.
So the perimeter of the track is less than 400 meters.
For the first lane on the track, the straightaway sections are each 84.39 meters long. However, the curved sections form a circle whose radius is now 36.5+1.22=37.72 meters. The diameter of the circle will be 2×37.72=75.44 meters. So the perimeter of lane 1 is
2×84.39+π×75.44≈405.78.
So the perimeter of lane 1 on the track is more than 400 meters and is almost 8 meters more than the perimeter of the inside of the track.
Suppose we let x denote the distance from the inside of lane 1 which gives a perimeter of 400 meters. This perimeter will be consist of the two straight sections which contribute 2×84.39 meters to the perimeter. In addition, there will be two semi-circular sections of radius 36.5+x meters. Combining these gives a circle whose diameter is 2×(36.5+x) meters. So we want
2×84.39+π×2×(36.5+x)=400.
Rewriting this we find
2π×x=400−2×84.39−2π×36.5
Solving for x we find
x≈0.30.
Note that this value for x is not exact but approximate. It is accurate to within about two ten thousandths of a meter or a fraction of a millimeter. So approximately 30 centimeters from the inside of lane 1 the perimeter of the track is 400 meters.