User's Manual

17-16 Applications
8317APPS.DOC TI-83 international English Bob Fedorisko Revised: 02/19/01 1:00 PM Printed: 02/19/01 1:39 PM
Page 16 of 20
Use the equation solver to store a formula for the area of a
regular N-sided polygon, and then solve for each variable,
given the other variables. Explore the fact that the limiting
case is the area of a circle,
p
r
2
.
Consider the formula A = NB
2
sin(
pà
N) cos(
pà
N) for the
area of a regular polygon with N sides of equal length and
B distance from the center to a vertex.
N = 4 sides N = 8 sides N = 12 sides
1. Press

0 to select 0:Solver from the
MATH
menu.
Either the equation editor or the interactive solver
editor is displayed. If the interactive solver editor is
displayed, press
}
to display the equation editor.
2. Enter the formula as
0=A
N
NB
2
sin(
p
/ N)cos(
p
/ N), and
then press
Í
. The interactive solver editor is
displayed.
3. Enter N=4 and B=6 to find the area (A) of a square with
a distance (
B) from center to vertex of 6 centimeters.
4. Press
} }
to move the cursor onto
A, and then press
ƒ
[
SOLVE
]. The solution for A is displayed on the
interactive solver editor.
5. Now solve for B for a given area with various number of
sides. Enter
A=200 and N=6. To find the distance B,
move the cursor onto
B, and then press
ƒ
[
SOLVE
].
6. Enter
N=8. To find the distance B, move the cursor onto
B, and then press
ƒ
[
SOLVE
]. Find B for N=9, and
then for
N=10.
Computing Areas of Regular N-Sided Polygons
Problem
Procedure