Answer:
4
Step-by-step explanation:
Area of Sector is
[tex] \frac{x}{2\pi} \pi {r}^{2} [/tex]
, where x is the central angle is radians.
If we know the area is 12 pi., central angle js 3 pi/2, we can solve for the area.
[tex] \frac{ \frac{3\pi}{2} }{2\pi} \pi {r}^{2} = 12\pi[/tex]
[tex] \frac{3}{4} \pi {r}^{2} = 12\pi[/tex]
[tex] \frac{3}{4} {r}^{2} = 12[/tex]
[tex] {r}^{2} = 16[/tex]
[tex]r = 4[/tex]
So the radius is 4