To find the maximum height you have to calculate the initial velocity in the y axis..
to do that resolve the velocity vector in the y direction
which is equal to vsin@
27*√3/2 = 23.4 m/s
thus using kinematics.
v^2 = u^2 + 2as
23.4*23.4 /19.6 = s
27.96 that's 28 m approximately
