The Geometer’s Sketchpad
®
for TI-89, TI-92 Plus, and
© 2000-2002 KCP Technologies, Inc.
9
Voyage™ 200 PLT User Guide and Reference Manual
5. Press
N
to return to the
Arrow, then press and hold
‚
(TI-89:
j
) while using
@
to
drag the circle’s two defining
points to be sure the circle and
segment are connected.
6.
Use the Segment tool to draw
another radius of the circle. Be
sure to place one endpoint with
the cursor positioned at the
circle’s center (
¸
) and the
other endpoint with the cursor
anywhere on the circle’s
circumference (
¸
).
7.
Construct a segment to connect
the two points on the circle and
complete the triangle.
8. Press
N
to return to the
Arrow. Then position it on a
vertex, press and hold
‚
(TI-89 :
j
), and press
@
to
drag the vertex. Drag the other
vertices too, and observe how
each changes the triangle.
Did you notice that two sides of this triangle always appear to stay equal?
Why? Did you notice that dragging one of the vertices didn’t change the
length of these equal sides? What’s different about that point?
You can automate dragging using animation. Follow these steps to animate
one vertex traveling around the circle.
Steps
Display
1. Press
N
to deselect all
objects. Press
¸
on the
point on the circle that does not
change the circle’s radius to
select it. If you’re not sure you
have the right point, drag it first.
2. Press
„
Display:
n
Animate
Point.
3. To stop the animation, Press
„
Display: (TI-89:
j
)
Ñ
Stop
Animation.
There should be only two
points in your sketch that
define both the segment and
the circle. If the circle
separates from the segment
when you drag, undo (
ƒ
¨
) until the circle is gone
and try again.
Remember: On the TI-89,
you can use
M
as a
shortcut for
¸
when
drawing or selecting objects.
(The
M
key might be
easier to reach.)
Animating
You’ve probably noticed that
pressing
¸
with the
Arrow over an object
changes the object’s
appearance to indicate
you’ve selected it. In
general, you need to select
objects that you want to act
upon with menu commands.