JAMB - Mathematics (2020 - No. 31)

The chord ST of a circle is equal to the radius r of the circle. Find the length of arc ST

\(\frac{\pi r}{3}\)

\(\frac{\pi r}{2}\)

\(\frac{\pi r}{12}\)

\(\frac{\pi r}{6}\)

\(\frac{ \frac{r}{2}}{r}\) Sin \(\theta\) = \(\frac{1}{2}\)

\(\theta\) = sin\(^{-1}\) (\(\frac{1}{2}\)) = 30\(^o\) = 60\(^o\)

Length of arc (minor)

ST = \(\frac{\theta}{360}\) x 2\(\pi r\)

\(\frac{60}{360} \times 2 \pi \times r = \frac{\pi}{3}\)