The projectile of Prob. 3/122 is repeated here. By the method of this article, determine...

The projectile of Prob. 3/122 is repeated here. By the method of this article, determine the vertical launch velocity v₀ which will result in a maximum altitude of R/2. The launch is from the north pole and aerodynamic drag can be neglected. Use g = 9.825 m/s² as the surface-level acceleration due to gravity.