Reference Guide
Equation Reference 5-45
Rectangle (11, 3)
Equations:
A b h⋅=
P 2 b⋅ 2+ h⋅= I
b h
3
⋅
12
-------------
=
J
b h⋅
12
----------
b
2
h
2
+( )⋅= Id I A+ d
2
⋅=
Example:
Given:
b=4_chain, h=7_rd, d=39.26_in. Set guesses for I, J, and Id in km^4.
Solution:
A=28328108.2691_cm^2, P=23134.3662_cm, I=2.9257E–7_km^4, J=1.8211E–6_km^4, Id=2.9539E–
7_km^4.
Regular Polygon (11, 4)
Equations:
A
1
4
-
-
-
n
L
2
⋅
⋅
T
A
N
180
n
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
=
P
n
L
⋅
=
r
s
L
2
-
-
-
T
A
N
180
n
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
=
r
v
L
2
-
-
-
S
I
N
180
n
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
=
θ
n
2
–
n
-
-
-
-
-
-
-
-
-
-
-
-
180
⋅
=
β
360
n
-
-
-
-
-
-
-
-
-
=
Example:
Given:
n=8, L= 0.5_yd.
Solution:
A=10092.9501_cm^2, P=365.7600_cm, rs=55.1889_cm, rv=59.7361,
θ
=135_°,
β
=45_°.