Question

A race track is in the form of
a ring whose inner circumference
is 770m. Find the width of the track.​

Answer 1

$c = 2\pi \: r \\ \\ 770 = 2\pi \: r \\ \\ r = \frac{770}{2\pi} \\ \\ r = \frac{770 \times 7}{2 \times 22} \\ \\ r = \frac{70 \times 7}{2 \times 2} \\ \\ r = 35 \times 3.5 \\ \\ r = 122.5 \\ \\ hence \: \\ \\ width \: \: \: \: of \: \: \: \: road \: \: \: = 2 \times 122.5 \\ \\ = 245$