Projectile Motion (in a vaccum)

[RogerDodgr]

issue resolved; thanks dick

Given are listed in photo:
t_f=time final (at impact)
y_max = max height
v_o = initial velocity
final height = initial height = 0
x_f =D = final distance

I am having a problem with this because I know max height time must be half of final time at impact (zero height):
http://www.sudokupuzzles.net/blstc.gif

 

[Dick]

You lost a cos(alpha) around the middle of the page. v0^2=16*D/(cos(alpha)^2*tan(alpha)). Note the squared on the cos(alpha).