Solve for r.
s=2πrhs=2πrh
s2π=rs2π=r
s2πh=rs2πh=r
s2=rs2=r
2πsh=r
s=2πrhs=2πrh
s2π=rs2π=r
s2πh=rs2πh=r
s2=rs2=r
2πsh=r