HP 39g+ User Manual page 25

Trig Explorer aplet
Getting started
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
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
keys transforms the
graph, with these
transformations reflected in the equation.
The button labelled
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
'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 sin bx
and
is
Origin
( π 2 1 , ⁄ )
.
Extremum
)
+ c + d
as the
is chosen the
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