Reference Guide

5-44 Equation Reference
Circle (11, 1)
Equations:
A π r
2
⋅=
C 2 π r⋅ ⋅=
I
π r
4
⋅
4
------------
=
J
π r
4
⋅
2
------------
=
Id I A+ d
2
⋅=
Example:
Given: r=5_cm, d=1.5_cm.
Solution: C=31.4159_cm, A=78.5398_cm^2, I=4908738.5_mm^4, J=9817477.0_mm^4, Id=6675884.4_mm^4.
Ellipse (11, 2)
Equations:
A π b h⋅ ⋅=
C 2 π
b
2
h
2
+
2
-----------------⋅ ⋅= I
π b h
3
⋅ ⋅
4
--------------------
=
J
π b h⋅ ⋅
4
------------------
b
2
h
2
+( )⋅= Id I A+ d
2
⋅=
Equations: Example:
Given: b=17.85_ µ m, h=78.9725_ µ in, d=.00000012_ft.
Solution: A=1.1249E–6_cm^2, C=7.9805E–3_cm, I=1.1315E–10_mm^4, J=9.0733E–9_mm^4,
Id=1.1330E–10_mm^4.