Texas Instruments -84 Plus, Manual Book

Page: 509 / 696

Chapter 17: Activities 506
Computing Areas of Regular N-Sided Polygons Computing Areas of Regular N-Sided Polygons Computing Areas of Regular N-Sided Polygons Computing Areas of Regular N-Sided Polygons
Problem
Problem Problem
Problem
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.
Procedure
Procedure Procedure
Procedure
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.
N = 4 sides
N = 8 sides
N = 12 sides