Vector Algebra

If \(\hat{\mathrm{a}}\) and \(\hat{\mathrm{b}}\) are unit vectors and \(\overline{\mathrm{c}}=\hat{\mathrm{b}}-(\hat{\mathrm{a}} \times \overline{\mathrm{c}})\), then minimum value of \([\hat{a} \hat{b} \bar{c}]\) is