Question

Find the radius of a circle whose arc length is 51 cm and its central angle is 3 radians.

Answer 1

we have

$\begin{gathered} s=r\theta \\ \end{gathered}$

where r is the radius, θ is the radian measure of the central angle, and s is the arc length, so

$\begin{gathered} 51=r3 \\ \frac{51}{3}=\frac{r3}{3} \\ r=17 \end{gathered}$

answer: radius = 17 cm