Answer:
7
Step-by-step explanation:
The length of the arc can be calculated via a simple proportion:
2 pi r : 360° = x : 45°
Where r is the radius of the circumference and x the length of the arc we want to know. Isolating the x:
x = (2 pi r : 360) * 45 = (2 pi * 9 : 180) * 45 = 18 pi : 360 * 45 = 18pi : 8 = 7
