Feathers<span> vary considerably in structure and </span>function<span>. </span>Contour feathers<span> form most of the surface of the bird, streamlining it for flight and often waterproofing it. The basal portion may be downy and thus act as insulation.
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The umbilical cord I believe
Answer: 26.75 meters.
2πr = 84
2 * 3.14 * radius = 84
radius = 84/6.28
r= 13.375
So the diameter will be 13.375 + 13.375 which is 26.75 meters.
