HP 39gs User Manual page 25

Trig Explorer aplet
Getting started
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.
Pressing displays the
equation at the top of the
screen. The equation is
controlled by the graph.
Pressing the and
keys moves from parameter
to parameter. Pressing the
parameter's values.
The default angle setting for this aplet is radians. The
angle setting can be changed to degrees by pressing
.
(
y = a sin bx
and
is
Origin
( π 2 1 , ⁄ )
.
Extremum
or
)
+ c + d
as the
is chosen the
key changes the
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