SOLUTION: The cross section of a pipe is formed by two concentric circles such that the bigger one circumscribes a regular hexagon of sides measuring 9.40 cm while the other one is inscribed

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Question 1153296: The cross section of a pipe is formed by two concentric circles such that the bigger one circumscribes a regular hexagon of sides measuring 9.40 cm while the other one is inscribed in it. Find the cross-sectional area of the pipe.
A.69.40 cm2
B.64.90 cm2
C.60.94 cm2
D.60.04 cm2

Answer by ikleyn(52788) About Me  (Show Source):
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The outer radius of the pipe is  R = 9.40 cm.


The interior radius of the pipe is the apothem of the regular hexagon, so its length is  r = 9.4%2Asqrt%283%29%2F2 = 8.14 cm.


The cross-sectional are is the difference of the area of the bigger and smaller circles


    pi%2AR%5E2 - pi%2Ar%5E2 = 3.14159%2A%289.4%5E2-8.14%5E2%29 = 69.43 cm^2.