3PT 2S (3 points, 2 slopes) allows you to create a conic
based on the positions for three points on the conic, and
the slope of the conic at two of the indicated points.

Indicate the start point of the conic, using a Position 
Menu option.

Indicate a second point of the conic, using a Position 
Menu option.

Indicate the endpoint of the conic, using a Position 
Menu option.

Slopes, (i.e., tangent vectors) must be assigned to two of
the three indicated points. You are prompted to key-in the
point number for the first slope.

To assign the first slope that you define to the start
point, press <Enter> only. To assign the first slope that
you define to the second or third indicated point, enter 
the desired point number and press <Enter>.

Define the slope of the conic at the selected point.

You are prompted to key-in the point number for the second
slope.

To assign the second slope that you define to the 
endpoint, press <Enter>. To assign the second slope that
you define to the first or second indicated point, enter 
the desired point number and press <Enter>.

Define the slope of the conic at the selected point.

If a conic cannot be created (e.g., indicated points are
coincident, a tangent vector points from one of the
indicated points to another indicated point), an error
message is displayed. You are prompted to press <Enter> 
and to redefine the conic, beginning with the position of 
the start point.

In 2-D construction mode, the indicated points and the
slopes are projected to the current construction plane. 
The conic is created in the current construction view, at 
the depth that is active when the second slope is defined.

In 3-D construction mode, the conic is created in the 
plane that is defined by the three indicated points. The 
tangent vectors are projected to this plane.
