I wish I had this book when I was taking Geometry!” — Amanda Borcky College student “Head First 2D Geometry is a clearly written guide to learn about two-dimensional shapes.. The ‘hands
Trang 3Advance Praise for Head First 2D Geometry
“Head First did it again The ability to make the reader understand, despite tricky topics, really shines
through in Head First 2D Geometry! The way the information is presented and organized makes learning
cohesive and easy Coming from someone who has struggled with many aspects of math in the past,
this book helps you understand the basics and build on them I wish I had this book when I was taking
Geometry!”
— Amanda Borcky
College student
“Head First 2D Geometry is a clearly written guide to learn about two-dimensional shapes The thorough
explanations of the material are adequate for both a first-time student and one needing a quick review
The ‘hands on’ approach gives a richer understanding of the material than would otherwise be obtained
from a traditional textbook.”
— Ariana Anderson
Statistician at UCLA’s Center for Cognitive Neuroscience
“Head First 2D Geometry helps you learn that plane geometry doesn’t have to be plain geometry This book
lets you see that geometry is not only in the classroom, it is all around you and a part of your everyday
life.”
— Herbert Tracey
Instructor of mathematical sciences at Loyola University Maryland and
former department chair of mathematics at Hereford High School
“Head First 2D Geometry is clear and readable, while other textbooks drag students through a thicket of
academic jargon Head First has interesting examples, fun design, and a conversational style that the
textbook industry would do well to emulate.”
— Dan Meyer
High school math teacher and recipient of Cable in the Classroom’s
Leader in Learning award
“Head First 2D Geometry grabs your attention with inventive and clever applied problems It pursues
thorough solutions with persistence and energy There is one character who appears throughout the
book and delights me—a serious, seemingly humorless girl who suspects the authors are trying to get
away with inconsistency and poor logic They always praise her questions and give in to her demands
that they level with her.”
— David Meyer
Trang 4Praise for other Head First books
“Head First Algebra is a clear, easy-to-understand method to learn a subject that many people find
intimidating Because of its somewhat irreverent attitude in presenting mathematical topics for beginners, this book inspires students to learn Algebra at a depth they might have otherwise thought unachievable.”
— Ariana Anderson
Statistician at UCLA’s Center for Cognitive Neuroscience
“The way Head First Algebra presents information is so conversational and intriguing it helps in the
learning process It truly feels like you’re having a conversation with the author.”
— Amanda Borcky
College student
“Head First Algebra has got to be the best book out there for learning basic algebra It’s genuinely
entertaining.”
— Dawn Griffiths
Author, Head First Statistics
“Head First Algebra is an engaging read The book does a fantastic job of explaining concepts and taking
the reader step-by-step through solving problems The problems were challenging and applicable to everyday life.”
— Shannon Stewart
Math teacher
“Head First Algebra is driven by excellent examples from the world in which students live No trains leaving
from the same station at the same time moving in opposite directions The authors anticipate well the questions that arise in students’ minds and answer them in a timely manner A very readable look at the topics encountered in Algebra 1.”
— Herbert Tracey
Instructor of mathematical sciences, Loyola University Maryland
“If you want to learn some physics, but you think it’s too difficult, buy Head First Physics! It will probably
help, and if it doesn’t, you can always use it as a doorstop or hamster bedding or something I wish I had
a copy of this book when I was teaching physics.”
— John Allister
Physics teacher
Trang 5Praise for other Head First books
“Head First Physics has achieved the impossible—a serious textbook that makes physics fun Students all
over will be thinking like a physicist!”
— Georgia Gale Grant
Freelance science writer, communicator, and broadcaster
“Great graphics, clear explanations, and some crazy real-world problems to solve! Head First Physics is full of
strategies and tips to attack problems It encourages a team approach that’s so essential in today’s work world.”
— Diane Jaquith
High school physics, chemistry, and physical science teacher
“Head First Physics is an outstandingly good teacher masquerading as a physics book! You never feel fazed
if you don’t quite understand something the first time because you know it will be explained again in a
different way and then repeated and reinforced.”
— Marion Long
Teacher
“Dawn Griffiths has split some very complicated concepts into much smaller, less frightening bits of stuff
that real-life people will find very easy to digest Head First Statistics has lots of graphics and photos that
make the material very approachable, and I have developed quite a crush on the attractive lady model
who is asking about gumballs on page 458.”
— Bruce Frey
Author, Statistics Hacks
“Head First Statistics is an intuitive way to understand statistics using simple, real-life examples that make
learning fun and natural.”
— Michael Prerau
Computational neuroscientist and statistics instructor, Boston University
“Thought Head First was just for computer nerds? Try the brain-friendly way with Head First Statistics and
you’ll change your mind It really works.”
— Andy Parker
“Down with dull statistics books! Even my cat liked Head First Statistics.”
— Cary Collett
Trang 6the index
perimeter of (see perimeter)
scaling (see scaling shapes)
similar (see similar shapes)
(see also specific shapes)
shooting example (see homicide example)
similar shapes, 58–63, 67, 77, 89, 100
proportional scaling of, 73–76
ratios for, 92–98
right triangles and, 120–122
(see also scaling shapes)
6-sided shapes (see hexagons)
skate ramp example, 104–147
multiple ramps, 132–135
perpendicular uprights, 106–131
rope swing, 139–147
sketches (see drawings)
speakers example, 170–180
spread angle of speakers, 170–172, 174
squares, 268
area of, 286
perimeter of, 286–287
similarity of, 77, 100
(see also quadrilaterals; regular polygons)
straight lines (see lines)
Super Triangles (Pythagorean triples), 146, 148
supplementary angles, 17–18, 47
T
3-sided shapes (see triangles)
3D shapes, volume of, 278–280
trapeziums, 270
trapezoids, 262, 267, 269, 272 area of, 260–265
bases of, 262 compared to parallelograms, 270 isosceles trapezoids, 267, 269 triangles
altitude line for, 144–145, 148 angles of, adding, 20–22, 46 angles of, estimating, 175–180 area of, 162–167, 202, 290–294 bisecting, 144–146
bounding rectangle for, 157–163 centers of, 181–188
equilateral triangles, 176, 188, 290–294, 318 hypotenuse of, 131, 138
isosceles triangles, 144–145, 175–180, 269 legs of, 131, 138, 141
medians of, 182, 202 perimeter of, 294 right triangles (see right triangles) scalene triangles, 194–198 similar triangles, 58–63, 67, 73–76
V
vertical angles, 19, 40, 47 volume of 3D shapes, 278–280
Z
Z patterns, in parallel lines, 40, 47