O'Reilly logo

Head First 2D Geometry by Dawn Griffiths, Stray

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

CHAPTER 7
your geometry toolbox
Your Geometry Toolbox
You’ve got Chapter 7 under
your belt and now you’ve
added regular polygons to
your toolbox. For a complete list
of tool tips in the book, head over to
www.headfirstlabs.com/geometry.
Ar
ea =
1/2
x P
erimeter
x Ap
othem
P
erimeter =
Number of sides
x Side length
Equil
ateral
tr
iangle ar
ea =
3 t
2
4
Circumradius:
radius of the circumcircle
Ap
othem:
radius of the incircle
Internal angle
=
(n x 180º) - 360º
n
(n is number of sides)
The apothem joins the center to the
middle of a side, bisecting it.
The circumradius joins the center to
a vertex.
The apothem meets the side at a
right angle.
The circumradius bisects the
internal angle.
318 Chapter 7

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required