Projectiles using calculus

Show that to hit a target h metres above what was its maximum range position on

a horizontal plane, the initial speed of a projectile projected at the same angle as before, must be increased from V to m/s (air resistance is neglected.)

Thanks

I had the equations of motion as

x =

and

y =

Putting y = 0

t = 0 or

thus max range is

new projectile must hit

--

what shall I do next?

I gather that my new speed must have theta in it. however, the question does not have a theta. There is nothing I can do that eliminates the theta. Is the question wrong?