[TR] slope calculation

[Randall]

> I think the problem will first be encountered when I drive up the ramp and
> find that the edge of the platform rubs against the floorboard at about a
> place near the front of the car's door.  However, what's the formula
> required
> to show that if the slope is gentle enough,no contact with the car's rails
> will be made.

Well, the important point is what angle does the board make with the
horizontal surface.  If you draw an imaginary line between the bottoms of
the tires, it will form a triangle with the two surfaces.  The height of
that triangle cannot exceed the ground clearance of the car.

Offhand, I'm pretty sure that the triangle height (for a given base and
upper angle) is maximum for an isosceles triangle, which would mean you only
need to evaluate that case, which makes it fairly easy.  Since the angles
add up to 180, you know all the angles; and since the bottom of the triangle
is the wheelbase of the car, you know that too.  Now just solve the triangle
to get the board angle.

Then armed with the board angle and the height of your platform, you can
calculate the required length of the board.

Randall