Max Range of Projectile on Non-Level Ground

[tman1]

My question is, derive an equation to find the maximum range of a projectile that's not on level ground. I am lost and i did attempt this, by making a diagram and subbing in what i thought i would need to use, but i still have not come up with the answer. please help

 

[The Bob]

My question is, derive an equation to find the maximum range of a projectile that's not on level ground. I am lost and i did attempt this, by making a diagram and subbing in what i thought i would need to use, but i still have not come up with the answer. please help

I think the best thing you can do is post whatever you have done. I could suggest a lot but I don't know what is making you go wrong.

The Bob (2004 ©)

 

[andrevdh]

Substitute
$$y=R\ sin\alpha$$
and
$$x=R\ cos\alpha$$
in the parabolic equation for the projectile.
The range will then be a function of $\theta$.The turning point of a function occurs where the derivative is zero...