Calculating Initial Speed of a Projectile Using Gravity, Height, and Range

[nobodyuknow]

Homework Statement

Find the initial speed (Vo) in Projectile motion in terms of
Gravity (g)
Height (H)
Range (R)

Homework Equations

Nothing has been given, however, have found these so far...

Initial Velocity = sqrt((1/2 * g * R^2)/(cos2θ * (R * tanθ + H))

And a few others which are irrelevant.

The Attempt at a Solution

My friends and I are all collaborating and the above formula is the closest thing we've come up with.
We've also resorted to looking up on Google and Yahoo answers without much luck. Similar questions have aroused on Physics Forums, but not quite what we're after.
Thanks :)

 

[nobodyuknow]

After literally, 3 hours of arithmetic. We got the final answer.

 

[emailanmol]

Hey,
Your answer is perfect :-)