Finding The Area Between Curves - Texas Instruments TI-84 PLUS - Graphing Calculator Manual Book

• You can graph the functions again by turning the functions off and then turning them back on
on the Y= editor or by using the FuncOFF and FuncON commands on the home screen.

Finding the Area between Curves

Problem
Find the area of the region bounded by:
f(x) =
2
300x / (x + 625)
g(x) =
3cos(.1x)
x =
75
Procedure
1. Press z. Select the default mode settings.
2. Press p. Set the viewing window.
Xmin=0
Xmax=100
Xscl=10
3. Press o. Turn off all functions and stat plots. Enter the upper and lower functions.
2
Y1=300X à (X +625)
Y2=3cos(.1X)
4. Press y /
to select
5
curve, and guess for the intersection toward the left side of the display. The solution is
displayed, and the value of
stored in and
Ans
5. Press y 5 to go to the home screen. Press y <
graphically.
Shade(Y2,Y1,Ans,75)
6. Press y 5 to return to the home screen. Enter the expression to evaluate the integral for
the shaded region.
fnInt(Y1 N Y2,X,Ans,75)
The area is
325.839962
Xres=1
Ymin= L 5
Ymax=10
Yscl=1
. The graph is displayed. Select a first curve, second
5:Intersect
at the intersection, which is the lower limit of the integral, is
X
.
X
.
and use to see the area
7 Shade(
Chapter 17: Activities 316