Getting started 1-15
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.
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   or   key changes the 
parameter’s values.
The default angle setting for this aplet is radians. The 
angle setting can be changed to degrees by pressing 
.
ya bxc+()d+sin=
Origin
π 21,⁄()
Extremum
hp40g+.book  Page 15  Friday, December 9, 2005  12:27 AM