HP hp39gPlus User Guide - Page 25

Trig Explorer aplet

Page 25 highlights

Trig Explorer aplet A button is provided to evaluate the student's knowledge. Pressing displays a target quadratic graph. The student must manipulate the equation's parameters to make the equation match the target graph. When a student feels that they have correctly chosen the parameters a button evaluates the answer and provide feedback. An button is provided for those who give up! The Trig Explorer aplet is used to investigate the behaviour of the graph of y = a sin(bx + c) + d as the values of a, b, c and d change, both by manipulating the equation and seeing the change in the graph, or by manipulating the graph and seeing the change in the equation. Press , select Trig Explorer, and then press to display the screen shown right. In this mode, the graph controls the equation. Pressing the and keys transforms the graph, with these transformations reflected in the equation. The button labelled a toggle between is Origin and . When is chosen, the 'point of control' is at the origin (0,0) and the and keys control vertical and horizontal transformations. When is chosen the 'point of control' is on the first extremum of the graph (i.e. for the sine graph at (π ⁄ 2,1) . The arrow keys change the amplitude and frequency of the graph. This is most easily seen by experimenting. Extremum Getting started 1-15

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Getting started
1-15
A
button is provided to
evaluate the student’s
knowledge. Pressing
displays a target quadratic
graph. The student must
manipulate the equation’s parameters to make the
equation match the target graph. When a student feels
that they have correctly chosen the parameters a
button evaluates the answer and provide feedback. An
button is provided for those who give up!
Trig Explorer aplet
The
Trig Explorer
aplet is used to investigate the
behaviour of the graph of
as the
values of
a
,
b
,
c
and
d
change, both by manipulating the
equation and seeing the change in the graph,
or by
manipulating the graph and seeing the change in the
equation.
Press
, select
Trig
Explorer
, and then press
to display the screen
shown right.
In this mode, the graph
controls the equation.
Pressing the
and
keys transforms the
graph, with these
transformations reflected in the equation.
The button labelled
is
a toggle between
and
. When
is chosen, the ‘point of
control’ is at the origin (0,0)
and the
and
keys control vertical and
horizontal transformations. When
is chosen the
‘point of control’ is on the first extremum of the graph (i.e.
for the sine graph at
.
The arrow keys change the
amplitude and frequency of
the graph. This is most easily
seen by experimenting.
y
a
bx
c
+
(
)
d
+
sin
=
Origin
π
21
,
(
)
Extremum