Applications 17-17
8317APPS.DOC TI-83 international English Bob Fedorisko Revised: 02/19/01 1:00 PM Printed: 02/19/01 1:39 PM
Page 17 of 20
Find the area given B=6, and N=10, 100, 150, 1000, and
10000. Compare your results with p62 (the area of a circle
with radius 6), which is approximately 113.097.
7. Enter B=6. To find the area A, move the cursor onto A,
and then press ƒ [SOLVE]. Find A for N=10, then
N=100, then N=150, then N=1000, and finally N=10000.
Notice that as N gets large, the area A approaches pB2.
Now graph the equation to see visually how the area
changes as the number of sides gets large.
8. Press z. Select the default mode settings.
9. Press p. Set the viewing window.
Xmin=0 Ymin=0 Xres=1
Xmax=200 Ymax=150
Xscl=10 Yscl=10
10.Press o. Turn off all functions and stat plots. Enter the
equation for the area. Use X in place of N. Set the graph
styles as shown.
11.Press r. After the graph is plotted, press 100 Í
to trace to X=100. Press 150 Í. Press 188 Í.
Notice that as X increases, the value of Y converges to
p62, which is approximately 113.097. Y2=pB2 (the area of
the circle) is a horizontal asymptote to Y1. The area of
an N-sided regular polygon, with r as the distance from
the center to a vertex, approaches the area of a circle
with radius r (pr2) as N gets large.