If the shortest distance between the lines \(\overset{\rightarrow}{r_1}=\alpha\hat i+2\hat j+2\hat k\) \(+\lambda(\hat i-2\hat j+2\hat k)\), λ ∈ R, α > 0 and \(\overset{\rightarrow}{r_2}=-4\hat i-\hat k\) \(+\mu(3\hat i-2\hat j-2\hat k)\), μ ∈ R is 9, then α is equal to _________.