To find radius $ r $ use formula:
$$ V = \dfrac{ h ^{ 2 } \cdot r \cdot \pi}{ 3 } $$After substituting $V = 1309\, \text{cm}$ and $h = 8\, \text{cm}$ we have:
$$ 1309\, \text{cm} = \dfrac{ 8\, \text{cm} ^{ 2 } \cdot r \cdot \pi}{ 3 } $$$$ 1309\, \text{cm} \cdot 3 = 8\, \text{cm} ^{ 2 } \cdot r \cdot \pi $$$$ 3927\, \text{cm} = 64\, \text{cm}^2 \cdot r \cdot \pi $$$$ r = \dfrac{ 3927\, \text{cm} }{ 64\, \text{cm}^2 \, \pi} $$$$ r = 19.5313\, \text{cm}^-1 $$