Answer:
πr`2+πr2=π(r`2+r2)
=π((r`+r)^2-2r`r)
58π=π((10)^2-2r`r)
58=100-2r`r
2r`r=42
r`r=21
r`=21/r
we know that: r`+r=10
21/r+r=10
(21+r^2)/r=10
21+r^2-10r=0
factorizeing:r=3or7
so r`=21/r=7or 3
