Blade
Blade
Tongue
Tongue
Geometric Development of Tetrahedron
with Steel Framing Square
Unit Run
Draw Right Triangle Base
Tongue
Unit Run
12"
Draw Right Triangle Hypotenuse
Blade
16
.9
7"
12"
Right Triangle D is the base triangle
of the Tetrahedron
12"
D
12"
Draw second Right Triangle using Height or Unit Rise
8"
se
Unit Rise
Tr
D
Connect right triangle
rise to base to produce
hypotenuse
Blade
Unit Run
SBE Builders 2008
"
A
.42
12"
14
16
.9
7"
Unit Run
ia
ng
le
Hy
po
te
nu
Tongue
D
12"
Right Triangle A is the
Common Rafter Triangle of the Tetrahedron
Page 1 of 7
n
To
Draw Unit Rise at right angle to
hypotenuse leg of triangle D
e
gu
8"
se
Ri
it
Un
Unit Rise
8"
A
A
D
Bl
ad
e
D
n
To
e
gu
Draw Right
Triangle Hypotenuse
A
Bl
ad
e
D
e
gu
n
To
Right Triangle C produces the
Hip Rafter Triangle of the Tetrahedron
Un
e
us
ten
po
A
Hy
D
Unit Run
te
Hy
po
C
nu
s
e
oten
Hyp
e
us
po
ten
Hy
e
nu
s
te
Hy
po
A
Unit Run
Bl
ad
Unit Run
Unit Run
use
use
oten
Hyp
D
e
se
se
Ri
Ri
it
it
Un
Unit Rise
Unit Rise
SBE Builders 2008
Page 2 of 7
8"
A
14
.42
"
16
C
12"
.9
7"
18.7
6"
8"
D
12"
Un
Unit Rise
C
us
eA
ote
n
A
Hy
p
Unit Run
Hy
po
t
C
en
u
se
D
use
Hy p
oten
A
nu
ote
A
Hy
p
DUnit Run
se
D
Unit Run
DUnit Run
Tongue
Tongue
Extend leg of
Triangle D the
length equal to
Hypotenuse A
Hypotenuse A
se
te
nu
po
C
Hy
Hyp
oten
use
C
se
Ri
it
se
Ri
it
Un
Unit Rise
Draw in Hypotenuse
Un
it
Blade
A
se
po
ten
u
A
Hy
po
Hy
Unit Run
D
te
n
us
e
oten
C
Hyp
Blade
use
C
se
Ri
Unit Rise
DUnit Run
e
us
en
t
po
Hy
C
E
Hypotenuse A
Tongue
Blade
Right Triangle E produces the
Roof Surface Triangle of the Tetrahedron
SBE Builders 2008
Page 3 of 7
8"
2"
A
14
.4
12"
16
.
C
97
"
18.7
6"
8"
D
6"
.7
18
14.42"
12"
E
Draw altitude height
construction line
in Triangle C
Altit
ude
Ton
gue
C
A
D
C
A
Bla
de
D
E
SBE Builders 2008
E
Page 4 of 7
Altit
Altit
ude
ude
ue
ng
To
C
e
ad
Bl
C
A
Draw a construction line
that extends Triangle D
hypotenuse line
D
D
E
de
C
E
Tongue
Altit
u
A
Draw a construction line that extends
Triangle D Unit Run
A
D
Blade
Altit
E
ude
C
A
ue
ng
D
Bl
ad
e
To
Draw a construction line at a right angle to
the Triangle D hypotenuse line
E
SBE Builders 2008
Page 5 of 7
e
gu
n
To
Altit
ude
C
A
a
Bl
de
D
E
Altit
ude
Draw Right Triangle Hypotenuse
C
A
D
se
Ri
Al
tit
it
ud
e
Un
Altit
ude
Unit Rise
use
eA
us
ten
po
Unit Run
nu
te
Hy
po
oten
Hyp
se
Hy
B
D
B
e
nus
A
ote
C
Hyp
D
C
E
e
us
en
ot
p
Hy
C
SBE Builders 2008
E
Hypotenuse A
Unit Run
Right Triangle B produces the
Hip Rafter Backing Triangle of the
Tetrahedron
Page 6 of 7
C
A
B
D
E
To
e
ng
gu
Tongue
To
ng
ue
Ton
gue
Tongue
Tongue
ue
n
To
Blade
Blade
Blade
Bla
de
Bl
ad
e
Bl
ad
e
Tongue
Bl
ad
e
Blade
SBE Builders 2008
Page 7 of 7