Chapter 3 - Radian Measure and the Unit Circle - Section 3.2 Applications of Radian Measure - 3.2 Exercises - Page 110: 6

$2$ radians

Step 1: The formula to be used here is $s=r\theta$ where s is the length of the arc intercepted, r is the radius and $\theta$ is the central angle of measure in radians. Step 2: $s=r\theta$ Step 3: $20=(10)(\theta)$ Step 4: Multiplying both sides by $\frac{1}{10}$, $20\times\frac{1}{10}=10\times\theta\times\frac{1}{10}$ Step 5: $\frac{20}{10}=\theta$ Step 6: $\theta=2$ radians