Properties of Plane Areas

 

·        Rectangles:  Area = base*height,    Io = base*(height³)/12

 

·        Triangles: Area = base*height/2,    Io = base*(height³)/36

 

·        Circles: Area = pi*radius²,    Io = pi*(radius⁴)/4

 

·        Semicircle (base horizontal): Area = pi*(radius²)/2,    Io ~ 0.1098*radius⁴

 

^{(Io is the moment of inertia of the shape about its own centroidal axis)}