Three particles of masses 1kg, 2kg and 3kg are acted upon by forces $\left(\widehat{i}+2\widehat{j}\right),\left(2\widehat{j}+3\widehat{k}\right)$ and $\left(\widehat{k}+3\widehat{i}\right)$ newton respectively. The angle made by the acceleration of centre of mass with X-axis is $\left(in{\cos }^{-1}\right)$