To solve part a, we going to need the circumference of a circle formula
[tex]2\pi r[/tex]
Being r the radius of the circle
So for our case:
[tex]2\pi\cdot4=8\pi[/tex]
Answer a: 8pi or 25.1
Now for the part b, we got
So let's set out this equation
[tex]\frac{\frac{\pi}{3}}{2\pi}=\frac{\beta}{2\pi r}[/tex]
In this case, beta is the length of AB and pi/3 is the conversion to radians of 60
Solving we get
[tex]\begin{gathered} \beta=\frac{\pi r}{3} \\ \\ \beta=\frac{4\pi}{3} \end{gathered}[/tex]
Answer b: 4pi/3 or 4.1889
