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Head First 2D Geometry by Dawn Griffiths, Stray

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T
he three fi
elds
ar
e diff
er
ent
s
hapes and sizes.
triangle properties
First we need to pick a venue
There are three local fields where this sort of event can take place,
and your choice of venue is absolutely critical. It determines how
many people can come to your festival and what it will cost to
make sure they all pay to get in.
Here are the three possible venues:
Field A
Field B
Field C
What do you need to find out about each potential venue to
figure out the following? Just describe these in normal words—
don’t worry about geometry jargon.
a) The fencing costs:
b) The capacity:
We don’t w
ant p
eople
coming in for f
r
ee!
T
he number of p
eople who
can come to the f
es
tiv
a
l
you are here 4 151
P as in P
er
imeter
T
hese line nota
tions mean the
length of the line segment
bet
ween those points.
W
ork
s f
or w
eird shapes, t
oo!
permeter is the total length of sides
What do you need to find out about each potential venue to
figure out the following? Just describe these in normal words—
don’t worry about geometry jargon.
a) The fencing costs:
b) The capacity
we don’t w
ant p
eople
coming in for f
r
ee!
number of p
eople who can
come t
o the f
es
tiv
a
l
The length of the edges
The area—how much space there is
If y
ou wrote “p
er
imeter,” tha
t’s
corr
ec
t, t
oo.
The perimeter is the total length of the sides of a shape
If you add up the lengths of all of the sides, or edges, of a
shape then you’ve got the perimeter. The exact calculation you
need to do depends on how many sides your shape has.
A
P = AB + BC + CA
B C
B
D
C
J
I
P = AB + BC + CD + DE + EF
A
E
+ FG + GH + HI + IJ + JA
F
G
H
152 Chapter 4

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