User's Manual

Geometry 139
point B (referred to as GB in Symbolic view) and the later
is to constrained to the slope of C (referred to as GC in
Symbolic view).
19. Yo u sh ou ld h av e point() on the entry line. Between
the parentheses, add:
abscissa(GB),slope(GC)
You can enter the commands by hand, or choose them from
one of two Toolbox menus: App > Measure, or
Catlg.
20.Tap .
The definition of your
new point is added to
Symbolic view. When
you return to Plot view,
you will see a point
named D and it will
have the same x-
coordinate as point B.
21. Press
P.
If you can’t see point D,
pan until it comes into
view. The y coordinate
of D will be the
derivative of the curve at
point B.
Since its difficult to read
coordinates off the screen, we’ll add a calculation that
will give the exact derivative (to three decimal places)
and which we can display in Plot view.
Add some
calculations
22. Press M.
Numeric view is where you enter calculations.
23. Tap .
24. Tap and choose Measure > slope
25.Between parentheses, add the name of the tangent,
namely GC, and tap .
Notice that the current slope is calculated and displayed.
The value here is dynamic, that is, if the slope of the