Operation Manual

14-20 Applications
8214APPS.DOC TI-82, Chapter 14, English Bob Fedorisko Revised: 02/09/01 9:27 AM Printed:
02/09/01 12:43 PM Page 20 of 20
Finding the Area between Curves
Find the area of the region bounded by:
f(x) = 300 x
à
(x
2
+ 625)
g(x) = 3 cos
.
1 x
x = 75
Procedure
1. Press
z
. Select the default
MODE
settings. Press
o
and turn off all
functions. Press
y
[
STAT PLOT
] and turn off all stat plots.
2. Press
p
. Set the viewing
WINDOW
.
Xmin = 0 Ymin =
M
5
Xmax = 100 Ymax = 10
Xscl = 10 Yscl = 1
3. Press
o
. Enter the upper and lower functions.
Y
1
=300X
à
(X
2
+625)
Y
2
=3cos .1X
4. Press
y
ã
CALC
ä
and select
intersection
. The graph is displayed. Select
First curve
,
Second curve
, and
Guess
for the intersection at the left of
the display. The solution is displayed, and the value of
X
at the
intersection, which is the lower limit of the integral, is stored in
Ans
and
X
.
5. Press
y
ã
DRAW
ä
and use
Shade(
to see the area graphically.
Shade(Y
2
,Y
1
,1,Ans,75)
6. Press
y
ã
QUIT
ä
to return to the Home screen. Enter the expression to
evaluate the integral for the shaded region.
fnInt(Y
1
–Y
2
,X,Ans,75)
The area is
325.839962
.