Answer:
D. 31.4cm
Explanation:
To know the measure of the arc AB, we must first know the measure of the perimeter (the circumference) of the circle:
![c=2\pi r](https://img.qammunity.org/2021/formulas/mathematics/middle-school/kbj7gky71m154h241gozhlumewbtlghg2n.png)
where
is a constant,
![\pi=3.1416](https://img.qammunity.org/2021/formulas/mathematics/middle-school/293528pzxwkmpnmm44291jkqlxbesfxjdh.png)
and
is the radius which is the line that goes from the center of the circle to a point on the circumference, in this case:
![r=30cm](https://img.qammunity.org/2021/formulas/mathematics/middle-school/ptovlfmrisvlt921wxtpl5x07lpedd5nri.png)
so the measurement of the circumference is:
![c=2(3.1416)(30cm)\\c=188.5cm](https://img.qammunity.org/2021/formulas/mathematics/middle-school/35xmp891eul1ky0uq89ky0eqxy0jk4hx48.png)
Now, we don't want the measurement of the entire circumference, we only want 60 ° of the total 360 ° degrees of the circle. For this we must divide the measure that we find for the circumference by 360 and multiply the result by 60:
which is option D