The formula for a circle's area is [tex]A=\pi r^2[/tex]. We are given an area of 38.465 square inches for a quarter of it.
Multiply this value by 4 to compensate for the quarter circle.
[tex]4 \times 38.465=\pi r^2[/tex]
[tex]153.86=\pi r^2[/tex]
Divide both sides by pi (Note: I'm using the conventional value of 3.14)
[tex]49=r^2[/tex]
Take the positive square root of both sides
[tex]7=r[/tex]
The radius is 7 inches. Let me know if you have any questions, thanks!