I'm trying to solve this function, I've already gotten it to work when I set r but now I'm trying to do it when r remains a variable but this keeps on telling me NSolve doesn't have the methods available. I've tried using an approximation of ArcCosx and switching to Reduce and I'm not sure what I could try next?
l = 1000000/(r^2 Pi);
a = h/r;
NSolve[50000*1/l == r^2 ArcCos[1 - a] - (r - h) Sqrt[2 r h - h^2], h, Reals]