Trig Explorer aplet 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

is

 

 

Origin

 

 

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 (π ⁄ 2,1) .

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.

Extremum

or key changes the

The default angle setting for this aplet is radians. The angle setting can be changed to degrees by pressing .

Getting started

1-15

Page 25
Image 25
HP 39gs Graphing manual Transformations reflected in the equation