Answer: [tex]\theta\approx1.78\ rad[/tex]
Step-by-step explanation:
By definition, the Arc lenght can be calculated with the following formula:
[tex]s=r\theta[/tex]
Where "s" is the Arc lenght, "r" is the radius and [tex]\theta[/tex] is the central angle measured in radians.
From that equation you can solve for [tex]\theta[/tex] dividing both sides of the equation by the radius "r", then:
[tex]\frac{s}{r}=\frac{r\theta}{r}\\\\\theta=\frac{s}{r}[/tex]
According to the information given in the exercise:
[tex]s=21.3\ in[/tex]
And you can identify in the figure that the radius of the circle is:
[tex]r=12\ in[/tex]
Therefore, you can substitute values into the equation:
[tex]\theta=\frac{21.3\ in}{12\ in}[/tex]
Finally, evaluating, you get the following result:
[tex]\theta=1.775\ rad[/tex]
Rounded to the nearest hundredth of a radian:
[tex]\theta\approx1.78\ rad[/tex]
