Consider the angle formed by the lines RS and RT. This is the angle that we want find. In general, for a circle, the arc formed by two lines that start at the center of the circle has a lenght that is related to the angle (in radians) formed by the lines and the radius of the circle by the following formula.
[tex]S\text{ = r }\theta[/tex]
where S is the arc lenght. In our case, we have
[tex]3\pi\text{ = r }\theta[/tex]
In this case, r is the radius of the circle, which is known to be the lenght of the line RS, which is 12.
So, we get the equation
[tex]3\pi=12\theta[/tex]
If we divide on both sides by 12, we get
[tex]\frac{3\pi}{12}=\theta=\frac{\pi}{4}[/tex]
so the angle is pi/4.. By using an approximation for the value of pi (3.1416) so you can find a value of theta of 0.785 radians, which rounded to the neares hundredth is 0.79 radians
