HP 40gs HP 39gs_40gs_Mastering The Graphing Calculator_English_E_F2224-90010.p - Page 95

The Expert: Vector Functions, Fun and games, Example 1

Page 95 highlights

12 THE EXPERT: VECTOR FUNCTIONS Fun and games Apart from the normal mathematical and engineering applications of parametric equations, some interesting graphs are available through this aplet. Three quick examples are given below. Example 1 Try exploring variants of the graph of: x(t ) = 3sin 3t y(t ) = 2sin 4t Example 2 Try varying the values of A and B in the equations: x1(t) = (A+ B)cos(t) − Bcos((AB +1)t) y1(t) = (A+ B)sin(t) − Bsin((A B +1)t) Hint: An easy way to vary A and B is to store values to memories A and B in the HOME view and enter the equations exactly as shown. New graphs can then be created by changing back to HOME and storing different values to A and B. The example shown uses A=4, B=2.5 and has axes set with TRng of 0 to 31.5 step .2, XRng of -21.66 to 21.66 and YRng of -12 to 9. It also has Axes un- 'd in PLOT SETUP. Example 2 Try varying the constants in the equations: x1(t) = 3sin(t) + 2sin(15t) y1(t ) = 3cos(t) + 2cos(15t) For those who remember them, this is curve like those produced by a "Spirograph". 95

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12
T
HE
E
XPERT
:V
ECTOR
F
UNCTIONS
Fun and games
Apart from the normal mathematical and engineering applications of parametric equations, some interesting
graphs are available through this aplet. Three quick examples are given below.
Example 1
Try exploring variants of the graph of:
()
=
3sin 3
t
xt
()
=
2sin 4
t
y t
Example 2
Try varying the values of
A
and
B
in the equations:
+
)
x
1(
t
)
=
(
A
B
)cos(
t
B
cos((
A
t
B
+
1) )
1(
+
)
yt
)
=
(
A
B
)sin(
t
B
sin((
A
t
B
+
1) )
Hint:
An easy way to vary A and B is to store values to memories
A
and
B
in the
HOME
view and enter the
equations exactly as shown. New graphs can then be created by changing back to
HOME
and
storing different values to
A
and
B
. The example shown uses
A=4
,
B=2.5
and has axes set with
TRng
of 0 to 31.5 step .2,
XRng
of -21.66 to 21.66 and
YRng
of -12 to 9. It also has
Axes
un-
’d in
PLOT SETUP.
Example 2
Try varying the constants in the equations:
x
1(
t
)
=
3sin(
t
)
+
2sin(15
t
)
1(
yt
)
=
3cos(
t
)
+
2cos(15
t
)
For those who remember them, this is curve like those produced by a “Spirograph”.
95