Question

I need help finding the radius.

Answer 1

Since the central angle is a right angle, the labeled arc is 1/4 of the total circumference of the circle. The circumference of a circle with radius
`r` is
`2\pi r`, so we have

`\frac{2\pi r}4=18\pi\,\mathrm{in}\implies r=36\,\mathrm{in}`