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Area, SM-Bank 150

The cross-section of the circular road tunnel, pictured below, has an area of \(46.24\pi \) square metres.
 

Calculate the radius of the tunnel.  (2 marks)

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\(6.8\ \text{m}\)

Show Worked Solution
\(A\) \(=\pi r^{2} \)
\(46.24 \pi\) \(= \pi r^2\)
\(r^{2}\) \(=46.24\)
\(r\) \(=\sqrt{46.24}\)
  \(=6.8\ \text{m}\)