The angle between the planes \(2x+y+z=7\) and \(x-y+2z=9\) is

\(120^{\circ}\) \(60^{\circ}\) \(30^{\circ}\) \(90^{\circ}\)

\(60^{\circ}\)

\(\cos \theta=\left|\frac{A_{1}A_{2}+B_{1}B_{2}+C_{1}C_{2}}{\sqrt{A_{1}^2+B_{1}^{2}+C_{1}^{2}}\sqrt{A_{2}^{2}+B_{2}^{2}+C_{2}^{2}}}\right|\)