The layout for a drop ogre is actually no different than a flat one, with the exception of the length of the cheek. For the drop cheek, because it sits on a slope, the length has increased. We use Pythagoras to find this new length. Once we have that, the process is the same. But, we have to remember to use this longer length in our calculation of the centerline radius.
(O2+L2) ÷ (4 x O) is our formula and the new, longer length must be used for the drop cheek.