L and H are known values, how do I get (solve) $RH$:
$RH * (1 – \cos ( \arctan(L/2 / RH ))) = H$
RH (not R*H) is circle radius
H is difference in beween radius and line crossing to circle.
L is length of line.
simply put, by replacing RH with R
$R * (1 – \cos ( \arctan(L/2 / R ))) = H$