[Krovin-Rezh]

There is a diagram on p60 of the rulebook that divides vehicle armour facing.

Going with this diagram, trace a straight line from the exact center of your vehicle to the corner, extending some length further. This line is the divide between the front and side armour "zones." Whichever zone the majority of the ramming vehicle is in should decide the matter.

Actually, you don't use the corners of your vehicles unless they happen to match up perfectly with the diagram on page 60. Just use a template that you've traced from that diagram and place it over the center of the vehicle to see the facing lines. Takeda had you on the right track, but just made a common and easy mistake about the corners.