Answer: 6 units
Step-by-step explanation:
90/360 = 1/4
We have 1/4 of a pizza here. This slice is equal to an area of 9pi square units. The full pizza is 4*9pi = 36pi square units.
Use the circle area formula to determine r.
A = pi*r^2
36pi = pi*r^2
36 = r^2
r = sqrt(36)
r = 6
The circle has radius 6 units.