Calculate the second moment of area (also known as moment of inertia of plane area, area moment of inertia, or second area moment) and the section modulus of a profile with polygonal cross section and side length *A*. Use this to calculate deflection or stress in a loaded profile.

\( I_{yy} = \dfrac {4\sqrt{3}A^{4}}{16} \)

\( W_{yy} = \dfrac {5A^{3}}{8} \)