I have R and I have A how do I solve for theta? From there I can figure out h.
Or is there another formula I could use to find h if I only have the Area and the radius?
First: This is a double posting which is against forum rules.
Second: You did not make clear that A is the area of the shaded area in the diagram.
Now I am prepared to be proven wrong in what follows.
It seems to me that your question has no unique solution.
As the circular radius increases and the angle $\displaystyle \theta$ decreases the area of the segment could remain constant.
Therefore, you need to know a third constant.
Thanks for trying, I have been fighting with this for awhile, but I found the answer.
You can use Newton's Method to solve for theta - sin(theta).
BTW the diagram is from the website you sent me to so I didn't think that I would have to explain it.
Sorry about the double post I was desperate to find the answer.